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Sleep and social status in captive gelada baboons (Theropithecus gelada)
Abstract
Sleep was investigated in 10 captive gelada baboons (Theropithecus gelada), belonging to two harem groups by continuous infrared video recording (n = 4 males, n = 3 females, n = 3 juveniles). The aim was to investigate the relation between sleep and social status. Social status was assessed during daytime activities, when the two harem groups interacted. Three behavioral states (waking, transitional sleep and relaxed sleep) as well as sleep fragmentation were scored based on movements and body posture. The individuals belonging to each of the harem groups spent most of the night huddled closely together within a sleeping cluster. Sleep was considerably fragmented in all adult and sub-adult individuals. No relation was found between sleep latency or sleep fragmentation and social rank. Total sleep time was 11.4 +/- 0.5 h per night (n = 10) and was negatively correlated with age. In the four males sleep duration was unrelated to their social rank, whereas both within the females and the juveniles it increased with decreasing rank. The amount of relaxed sleep was lower in the dominant males and the dominant females compared to the corresponding low-ranking ones. In contrast, dominant males had the highest amount of transitional sleep, while in the females no rank-association was evident. These results indicate that the high-ranking geladas engaging less in a relaxed sleeping posture may be maintaining a larger degree of alertness that would enable them to react quickly to nocturnal dangers.
... It has also been hypothesized that social species have to invest more time in social interactions and relationships, which in effect leaves them with less time to sleep ( Capellini et al., 2009). In primates, it has been proposed that hierarchy may play a role in the manifestation of the sleep patterns that are observed ( Noser et al., 2003). Male Gelada baboons show no correlation between sleep duration and social rank, whereas females and juveniles exhibit an increase in sleep duration with decreasing rank ( Noser et al., 2003). ...
... In primates, it has been proposed that hierarchy may play a role in the manifestation of the sleep patterns that are observed ( Noser et al., 2003). Male Gelada baboons show no correlation between sleep duration and social rank, whereas females and juveniles exhibit an increase in sleep duration with decreasing rank ( Noser et al., 2003). Furthermore, dominant male Gelada baboons have an increased amount of transitional sleep, which indicates that increasing rank leads to a decreased amount of relaxed sleep, which may in turn lead to an increased degree of vigilance, enabling these animals to react swiftly to nocturnal dangers. ...
... Furthermore, dominant male Gelada baboons have an increased amount of transitional sleep, which indicates that increasing rank leads to a decreased amount of relaxed sleep, which may in turn lead to an increased degree of vigilance, enabling these animals to react swiftly to nocturnal dangers. This study also indicated that no correlation existed between sleep fragmentation and social rank ( Noser et al., 2003). It has also been shown that group or network size in primates does not correlate with sleep times ( Nunn et al., 2010); however, when Drosophila was placed in a socially enriched environment they exhibited an increase in daytime, but not night time, sleep ( Ganguly-Fitzgerald et al., 2006). ...
The rock hyrax, Procavia capensis, is a highly social, diurnal mammal. In the current study several physiologically measurable parameters of sleep, as well as the accompanying behavior, were recorded continuously from five rock hyraxes, for 72 h under solitary (experimental animal alone in the recording chamber), and social conditions (experimental animal with 1 or 2 additional, non-implanted animals in the recording chamber). The results revealed no significant differences between solitary and social conditions for total sleep times, number of episodes, episode duration or slow wave activity (SWA) for all states examined. The only significant difference observed between social and solitary conditions was the average duration of rapid eye movement (REM) sleep episodes. REM sleep episode duration was on average 20 s and 40 s longer under social conditions daily and during the dark period, respectively. It is hypothesized that the increase in REM sleep episode duration under social conditions could possibly be attributed to improved thermoregulation strategies, however considering the limited sample size and design of the current study further investigations are needed to confirm this finding. Whether the conclusions and the observations made in this study can be generalized to all naturally socially sleeping mammals remains an open question.
... Data from captive primate populations have yielded similar findings. Although primate sleep patterns have traditionally been researched in terms of electrophysiological architecture (e.g., rhesus macaques: Weitzman et al. 1965; pig-tailed macaques: Reite et al. 1965;baboons: Bert et al. 1975), non-invasive methods, such as infrared video recording (e.g., Noser et al. 2003) and ultra sensitive video cameras (e.g., Munoz-Delgado et al. 1995) are increasingly being employed to investigate behavioural, rather than structural, characteristics of sleep. Evidence from laboratory-housed adult stump-tailed macaques (M. ...
... Adult male rhesus monkeys move to the periphery of sleeping groups on reaching maturity (Vessey 1973), as do maturing chimpanzee males (Goodall 1962). Dominant individuals in a zoo-housed baboon group (Noser et al. 2003) remained more alert during the night, adopting less relaxed postures than their subordinate counterparts. Laboratory housed pig-tailed macaque infants of dominant mothers had shorter sleep latencies compared to infants of mid/low-ranked females (Reite et al. 1976), attributed to dominant mothers being more able to select a secure space than lower-ranked individuals. ...
... Munoz-Delgado et al. 2004a). Zoo-housed gelada baboons also frequently left sleeping huddles, changed position, and even left the sleep site(Noser et al. 2003). ...
... However, some studies have investigated intrinsic and extrinsic factors influencing sleep patterns in nonhuman primates, such as abiotic environmental conditions, social status, and rearing history (Campbell and Tobler 1984). For instance, total sleep time decreases in captive chimpanzees (Pan troglodytes) as maximum relative humidity increases (Videan 2006); the amount of "relaxed" sleep, defined as sleep where the head is held on the chest, is lower in dominant male and female geladas (Theropithecus gelada) compared with lower-ranking group members (Noser et al. 2003), and nursery-reared rhesus macaques (Macaca mulatta) have shorter nocturnal sleep durations than mother-reared monkeys (Barrett et al. 2009). Moreover, total sleep duration correlates negatively with age in geladas (Noser et al. 2003) and humans (Carskadon and Dement 2000), but is positively related to age in owl monkeys (Aotus azarae: Suzuki and Sri Kantha 2006) and chimpanzees (Videan 2006). ...
... For instance, total sleep time decreases in captive chimpanzees (Pan troglodytes) as maximum relative humidity increases (Videan 2006); the amount of "relaxed" sleep, defined as sleep where the head is held on the chest, is lower in dominant male and female geladas (Theropithecus gelada) compared with lower-ranking group members (Noser et al. 2003), and nursery-reared rhesus macaques (Macaca mulatta) have shorter nocturnal sleep durations than mother-reared monkeys (Barrett et al. 2009). Moreover, total sleep duration correlates negatively with age in geladas (Noser et al. 2003) and humans (Carskadon and Dement 2000), but is positively related to age in owl monkeys (Aotus azarae: Suzuki and Sri Kantha 2006) and chimpanzees (Videan 2006). Thus, the length of sleep (Carskadon and Dement 2000) could be useful to evaluate the sleep characteristics of primates. ...
Little is known as to the influence of captivity and stressful events on sleep patterns in primates. We investigated the sleep patterns of 19 male chimpanzees living under similar conditions at the Chimpanzee Sanctuary Uto (CSU) in Kumamoto, Japan, using a behavioral sleep index. We conducted nighttime observations of all subjects during a stable period and then observed three subjects after relocation to an unfamiliar facility at CSU. We estimated length of sleep and nonsleep periods over 13-h video recordings using instantaneous sampling at 1-min intervals to record sleep, which we defined operationally as an inactive posture with the body lying down with the head on the floor or on nesting materials. The 19 subjects slept for a mean ± SEM of 11.3 ± 0.26 h during the stable period, and sleep patterns varied significantly among the subjects. The three relocated subjects all showed temporarily decreased sleep duration in the post-move period but subsequently recovered to the levels observed during the stable period when habituated to the new living quarters. These results suggest that a stressful event may induce temporary sleep shortage lasting for >1 wk in captive chimpanzees. Sleep patterns may serve as a useful behavioral index of the stress response, as it is less confounded by other behaviors and the actions of human caretakers than other indices.
... We recorded the number and length of each behavior that happened within an hour. To analyze night-time sleep, we studied the amount of time spent awake and asleep during the night [48 ]. The results revealed that there was no significant variation in self-injuring behaviors and stereotypical behaviors between the two groups ( Supplementary Table S8 ), implying that SRGAP2C had no effect on the mental state of the TG monkeys. ...
Human-specific duplicated genes contributed to phenotypic innovations during the origin of our own species, such as an enlarged brain and highly developed cognitive abilities. While prior studies on transgenic mice carrying the human-specific SRGAP2C gene have shown enhanced brain connectivity, the relevance to humans remains unclear due to the significant evolutionary gap between humans and rodents. In this study, to investigate the phenotypic outcome and underlying genetic mechanism of SRGAP2C, we generated transgenic cynomolgus macaques (Macaca fascicularis) carrying the human-specific SRGAP2C gene. Longitudinal MRI imaging revealed delayed brain development with region-specific volume changes, accompanied by altered myelination levels in the temporal and occipital regions. On a cellular level, the transgenic monkeys exhibited increased deep-layer neurons during fetal neurogenesis and delayed synaptic maturation in adolescence. Moreover, transcriptome analysis detected neotenic expression in molecular pathways related to neuron ensheathment, synaptic connections, extracellular matrix and energy metabolism. Cognitively, the transgenic monkeys demonstrated improved motor planning and execution skills. Together, our findings provide new insights into the mechanisms by which the newly evolved gene shapes the unique development and circuitry of the human brain.
... Because infants are more often targeted by predators, it is in the interest of dominant individuals to remain more alert and protect the group (Arlet and Isbell, 2009;Watts and Mitani, 2015). This hypothesis was supported by a study on captive gelada baboons that found that the amount of relaxed sleep was less in dominant individuals compared to subordinate individuals (Noser et al., 2003). Lesku et al. (2008) investigated how a predator chase affected subsequent sleep in Norway rats by chasing wild-caught rats around their cage with a gloved hand. ...
Social status among group-living mammals can impact access to resources, such as water, food, social support, and mating opportunities, and this differential access to resources can have fitness consequences. Here, we propose that an animal's social status impacts their access to sleep opportunities, as social status may predict when an animal sleeps, where they sleep, who they sleep with, and how well they sleep. Our review of terrestrial mammals examines how sleep architecture and intensity may be impacted by (1) sleeping conditions and (2) the social experience during wakefulness. Sleeping positions vary in thermoregulatory properties, protection from predators, and exposure to parasites. Thus, if dominant individuals have priority of access to sleeping positions, they may benefit from higher quality sleeping conditions and, in turn, better sleep. With respect to waking experiences, we discuss the impacts of stress on sleep, as it has been established that specific social statuses can be characterized by stress-related physiological profiles. While much research has focused on how dominance hierarchies impact access to resources like food and mating opportunities, differential access to sleep opportunities among mammals has been largely ignored despite its potential fitness consequences.
... Dominant individuals can also exhibit signs of chronic arousal likely related to the vigilance needed to maintain social status. High-ranking individuals have been shown to have reduced levels of deep sleep and increased sleep fragmentation in mice and baboons [94,95], but the extent to which this is common across species remains to be determined. These changes may be in part mediated by altered GC functioning, but may also occur through other mechanisms. ...
Individuals occupying dominant and subordinate positions in social hierarchies exhibit divergent behaviours, physiology and neural functioning. Dominant animals express higher levels of dominance behaviours such as aggression, territorial defence and mate-guarding. Dominants also signal their status via auditory, visual or chemical cues. Moreover, dominant animals typically increase reproductive behaviours and show enhanced spatial and social cognition as well as elevated arousal. These biobehavioural changes increase energetic demands that are met via shifting both energy intake and metabolism and are supported by coordinated changes in physiological systems including the hypothalamic–pituitary–adrenal and hypothalamic–pituitary–gonadal axes as well as altered gene expression and sensitivity of neural circuits that regulate these behaviours. Conversely, subordinate animals inhibit dominance and often reproductive behaviours and exhibit physiological changes adapted to socially stressful contexts. Phenotypic changes in both dominant and subordinate individuals may be beneficial in the short-term but lead to long-term challenges to health. Further, rapid changes in social ranks occur as dominant animals socially ascend or descend and are associated with dynamic modulations in the brain and periphery. In this paper, we provide a broad overview of how behavioural and phenotypic changes associated with social dominance and subordination are expressed in neural and physiological plasticity.
This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
... For diurnal species, it is presumed that most of their resting budget coincides with nocturnal periods, and that roost sites-defined as the nocturnal location of an individual (Jirinec et al., 2016) are the locations in which they select to rest. Resting (and associated sleep) is an adaptive behavior in nearly all animals that is dynamic in nature and dependent upon physiology, body condition, and social (Noser et al., 2003) and environmental cues (Lima et al., 2005). Resting behavior, along with the selection of sites to rest in, has direct implications on many important physiological demands (i.e., energy budgets [Walsberg, 1983, Pravosudov andLucas, 2000]; thermoregulation [Chruszcz and Barclay, 2002]) and survival mechanisms such as predator avoidance (Lima et al., 2005). ...
All animals must select sites to rest and may spend a large portion of their lives doing so. Despite the importance of this period in their daily activity budget, we lack information about rest/roost ecology for most animals, including the imperiled lesser prairie-chicken (Tympanuchus pallidicinctus; hereafter “LEPC”). Therefore, we sought to identify how landcover, anthropogenic features, and human policy (i.e., presence of the Conservation Reserve Program [CRP]) influenced roost site selection and movement patterns of the LEPC. From March to May 2013-2015, we captured and fitted GPS transmitters to 106 LEPCs (n = 72 males; n = 34 females) within Beaver County, Oklahoma and recorded two nocturnal locations per 24-hour period, annually. We used discrete choice models and generalized linear mixed effects models to determine how vegetation cover, CRP patches, and anthropogenic features influenced roost site selection and movements to roosting sites, respectively. We found that roost sites were closer to CRP, leks, and croplands than would be expected at random. Conversely, roost sites were located farther away from shortgrass prairie, roads, and transmission lines than expected. The probability of a LEPC roosting in a location increased by 15% and 4.5% for every 36-meter decrease in distance to a CRP patch and distance to their lek of capture, respectively. Similarly, individuals roosting in CRP patches would travel shorter distances to get to roost sites if their last diurnal location was near CRP. Bird’s movements to roosts in CRP were 1.4 times shorter for every meter decrease in the distance of their last diurnal location to a CRP patch, indicating that individuals modify their movement based on CRP presence. Our results indicate that CRP is influential to roosting ecology of the LEPC within this region and may be meeting critical cover requirements.
... The 5 viewers who were blind to the experimental design analyzed each night of video recording simultaneously using a standardized behavioral classification independently, and the inter-rater correlation coefficient was found to be >0.90 through SPSS statistical analyses. Three behavioral states, wake, transitional, and relaxed sleep, were scored in 1-minute epochs (Noser et al. 2003). States lasting <30 s were not considered, whereas states lasting between 30 and 59 s were rounded to 1 min. ...
To explore the brain structural basis underlying the behavioral abnormalities associated with Rett syndrome (RTT), we carried out detailed longitudinal noninvasive magnetic resonance imaging analyses of RTT monkey models created by gene-editing, from weaning, through adolescence, till sexual maturation. Here, we report abnormal developmental dynamics of brain white matter (WM) microstructures and network topological organizations via diffusion tensor imaging. Specifically, disrupted WM microstructural integrity was observed at 9 months, but recovered thereafter, whereas WM network topological properties showed persistent abnormal dynamics from 9 to 37 months. Changes in the WM microstructure and WM network topology were correlated well with RTT-associated behavioral abnormalities including sleep latency, environmental exploration, and conflict encounters. Deleterious and protracted early WM myelination process likely lead to abnormal synaptic pruning, resulting in poor functional segregations. Together, this study provides initial evidence for changes in WM microstructure and network topological organization, which may underlie the neuro-patho-etilogy of RTT.
... Behaviors were scored by three raters independently who were blind to the experimental design. Three behavioral states, awake, transitional and relaxed sleep were scored in 1 min epochs (Noser et al., 2003). States lasting < 30 s were not considered, whereas states lasting between 30 and 59 s were rounded to 1 min. ...
Gene-editing technologies have made it feasible to create nonhuman primate models for human genetic disorders. Here, we report detailed genotypes and phenotypes of TALEN-edited MECP2 mutant cynomolgus monkeys serving as a model for a neurodevelopmental disorder, Rett syndrome (RTT), which is caused by loss-of-function mutations in the human MECP2 gene. Male mutant monkeys were embryonic lethal, reiterating that RTT is a disease of females. Through a battery of behavioral analyses, including primate-unique eye-tracking tests, in combination with brain imaging via MRI, we found a series of physiological, behavioral, and structural abnormalities resembling clinical manifestations of RTT. Moreover, blood transcriptome profiling revealed that mutant monkeys resembled RTT patients in immune gene dysregulation. Taken together, the stark similarity in phenotype and/or endophenotype between monkeys and patients suggested that gene-edited RTT founder monkeys would be of value for disease mechanistic studies as well as development of potential therapeutic interventions for RTT.
... Yang et al. (2007) studied life activities of Francois' langur (Trachypithecus francoisi) in wildness and found out that -in spite of the fact that their locomotion activities of these monkeys are nearly the same as those of geladasthe share of foraging was nearly by one half lower (31.6 ± 7.86 %) than that our experimental group that was raised in captivity (55.3 ± 2.0 %). Problems concerning social relationships existing among adult baboons were dealt with by a number of authors (Noser et al., 2003;Yang et al., 2007;Mancini and Palagi, 2009). Playing is considered as one of the most important forms of social behaviour. ...
This study was focused on the monitoring of behaviour and complex social relationships existing among gelada (Theropithecus gelada) monkeys. The study involved a group of fi ve males that were raised in captivity in the Zoo Zlín - Lešná. Ethological monitoring was performed by means of photographing of the group behaviour of these animals. Studied were the basic forms of social behaviour, i.e. food collection (foraging), free movement, (locomotion) observing of the neighbourhood (watching), grooming, climbing on trees, playing, aggressive behaviour (fi ghting), and resting. The temporary point of view, foraging was the most important time-consuming activity (55.3 ± 2.0 % of the study time); its maximum frequencies occurred in time intervals of 9 and 11 a.m. and 1 to 3 p.m.. The second place was occupied by the locomotion (15.3 ± 4.1 % of the study time) and its maximum frequencies were recorded between 9 and 11 a.m. and between 2 and 3 p.m. Grooming was the third most important activity (8.5 ± 4.8 % of the study time). The distribution of periods of rest (7.5 ± 3.1 % of the study time) was relatively uniform and its maxima were observed between 10:30 a.m. and 4 p.m. Observing of the neighbourhood and climbing on trees occupied 5.6 ± 3.3 % and 3.6 ± 3.0 % of the time, respectively and playing was the least frequent activity (2.2 ± 9.0 % of the study time), similarly as the aggressive behaviour (2.0 ± 23.0 % of the study time).
... Research on the social determinants of variation in human sleep has shown that sleeping partners can influence sleeping time both positively and negatively (Troxel et al., 2007). In non-human primates, some social relationships can detract from sleeping because individuals devote time to social interactions to solidify their social status (Noser et al., 2003). Alternatively, congregating with familiar individuals might alleviate social stress and anxiety (Kikusui et al., 2006), which could in turn improve sleep quality (Dugovic et al., 1999). ...
Co-sleeping behaviour, such as sharing a sleeping site or bed, should play an important role in determining sleep structure in mammals by mitigating predation pressure and harsh abiotic conditions during sleep. Although environmental factors surrounding sleeping sites have been studied, there is very little information on the effects of the social environment within the site on sleep in animals other than humans. Here, we quantified the duration of nighttime sleep of wild primates during behavioural observations. Wild Japanese macaques (Macaca fuscata yakui) form clusters at sleeping sites, where they huddle with group members. Macaques slept for longer when huddled in sleeping clusters with natal members than in those with non-natal members. A high degree of synchronisation of wakefulness in pairs of macaques huddling in non-natal clusters suggested that their sleep was often interrupted by the wakefulness of huddling members at night. Our results suggest that familiarity and closeness to huddling partners influence sleep duration.
... Conversely, a species that is mostly predated by a specialist predator would benefit little from modifying its activity pattern, because the predator would adjust its own activity in accordance with that of the prey (Lima et al., 2005). Finally, drowsiness may represent a " state of vigilance with light sleep " that allows species under intense predation pressure to gain some of the benefits of sleep without the additional vulnerability associated with deeper sleep stages (Lima et al., 2005; Makeig, Jung, & Sejnowshi, 2000; Noser, Gygax, & Tobler, 2003). ...
All mammals so far studied experience some form of sleep. When mammals are sleep-deprived, they generally attempt to regain the lost sleep by exhibiting a “sleep rebound,” suggesting that sleep serves important functions that cannot be neglected (Siegel, 2008; Zepelin, 1989; Zepelin, Siegel, & Tobler, 2005). When sleep deprivation is enforced on individuals, it is accompanied by impaired physiological functions and a deterioration of cognitive performance (Kushida, 2004; Rechtschaffen, 1998; Rechtschaffen & Bergmann, 2002). In the rat, prolonged sleep deprivation ultimately results in death (Kushida, 2004; Rechtschaffen & Bergmann, 2002). Together, these observations suggest that sleep is a fundamental requirement for mammalian life, and much research has focused on identifying the physiological benefits that sleep provides (Horne, 1988; Kushida, 2004). Are there also costs associated with sleep? If so, what are the selective pressures that constrain the amount of time that individuals can devote to sleep? Sleep is probably associated with “opportunity costs” because sleeping animals cannot pursue other fitness-enhancing activities, such as locating food, maintaining social bonds, or finding mates. Sleeping animals may also pay direct costs. For example, sleep is a state of reduced consciousness, and thus sleeping individuals are less able to detect and escape from approaching predators (Allison & Cicchetti, 1976; Lima, Rattenborg, Lesku, et al., 2005). These ecological factors are likely to be important constraints on sleep durations and may also affect how sleep is organized over the daily cycle.
... Allison & Cicchetti 1976;Meddis 1983;Campbell & Tobler 1984;Tobler 1995;Zepelin 2000), and all have chosen not to treat it as a form of sleep. However, drowsiness is in many ways a particularly vigilant form of sleep (Makeig et al. 2000;Noser et al. 2003), and might be an effective way of dealing with the problem of predator detection. ...
Every studied animal engages in sleep, and many animals spend much of their lives in this vulnerable behavioural state. We believe that an explicit description of this vulnerability will provide many insights into both the function and architecture (or organization) of sleep. Early studies of sleep recognized this idea, but it has been largely overlooked during the last 20 years. We critically evaluate early models that suggested that the function of sleep is antipredator in nature, and outline a new model in which we argue that whole-brain or ‘blackout’ sleep may be the safest way to sleep given a functionally interconnected brain. Early comparative work also suggested that the predatory environment is an important determinant of sleep architecture. For example, species that sleep in risky environments spend less time in the relatively vulnerable states of sleep. Recent experimental work suggests that mammals and birds shift to relatively vigilant (lighter) states of sleep in response to an increase in perceived risk; these results mirror the influence of stress on sleep in humans and rats. We also outline a conceptual model of sleep architecture in which dynamic changes in sleep states reflect a trade-off between the benefits of reducing a sleep debt and the cost of predation. Overall, many aspects of plasticity in sleep related to predation risk require further study, as do the ways in which sleeping animals monitor predatory threats. More work outside of the dominant mammalian paradigm in sleep is also needed. An ecologically based view of sleeping under the risk of predation will provide an important complement to the traditional physiological and neurological approaches to studying sleep and its functions.
... Pursuing with the absence of a significant correlation between sleep and phylogeny, Noser et al. 39 explain that sleep has been investigated in 17 primate species showing: (i) that sleep stages as well as the composition of sleep cycles are similar to those of humans and (ii) inter-species differences have been found, with low amounts of deep sleep in species with intense nocturnal predation pressure (references therein). We are glad to see that this study confirms one of the conclusions of Lesku et al. 38 On the other hand we regret the absence of relation between encephalization and sleep in an analysis performed within a single phylogenetic branch and we feel compelled to believe that such relationship does not exist. ...
Introduction
Our main interest in writing a review on the trivial nature of sleep1 was asserting that the main function of sleep is merely adapting the activity of the organism to the light-dark cyclic changes of the planet but also to confront the triviality of sleep with the non-trivial functions of wakefulness. We are happy to see that our viewpoint has provoked a discussion on many aspects of sleep which in our opinion are taken for granted but actually lack sufficient objective support. We are thus grateful to Rattenborg and co-workers2 for having accepted the invitation to criticize our review. We examine next these criticisms.
... In general prior reports have indicated that the variability in sleep parameters between consecutive days in individual animals is low. The coefficient of variation (i.e., standard deviation/mean, calculated by the authors based on the published data) of total sleep time in individual animals ranges from 8 to 39% in elephants [37], 8–38% in giraffes [38], and 9–16% in baboons [27]. EEG studies on individually housed freely moving primates or herbivores also showed a relatively low level of variability in total sleep time (e.g., 4–14% in the Macaca mulatta [7]; 2–36% in ponies [8]; 23–41% in sheep [33]). ...
In this study we examined behavioral sleep in the walrus, the only living species of the family Odobenidae. The behavior of four 1.5-2-year-old captive walruses was videotaped continuously for 7-17 days and scored in 1-min epochs. When walruses had access to water and land, behavioral sleep, the combined amount of quiet and rapid eye movement (REM) sleep, occupied on average 17+/-4% of 24 h (n=4) with the majority of sleep occurring on land. All walruses alternated periods of almost continuous swimming lasting for 40-84 h with periods of rest on land lasting for 2-19 h. When in water they were predominantly awake (88-99% of the time). On land walruses were asleep on average 40-74% of the time. The total sleep time varied between 0 and 60% of 24h with the daily amount of REM sleep ranging from 0 to 5% of 24 h. In water, walruses slept while floating at the surface, lying on the bottom or standing and leaning against the pool wall. REM sleep in water occurred in all positions. On land the breathing pattern was regular during quiet sleep (most pauses were <30s) and arrhythmic in REM sleep (apneas lasted up to 160 s). While in water the irregularity of breathing further increased (apneas were >4 min) and all REM sleep episodes occurred during a single apnea. Data indicate that the pattern of sleep and breathing in walruses is similar to the Otariidae seals while on land and the Phocidae seals while in water.
Environmental variables have a major influence on the sleep patterns of animals, and can be presumed to have a strong role in the evolutionary paths of sleep in humans. Despite this understanding, only a few primate species have been systematically studied in their natural habitat, with research lacking on sleep characteristics in wild primates. Due to the difficulties of measuring sleep in the wild, primatology has largely focused on sleep through measurements of activity patterns, sleep ecology and habitat, which are assumed to reflect sleep patterns. I propose that advances in non-invasive technologies provide new opportunities for expanding sleep research in wild settings, and that well-known phenotypic variability in sleep across species represents an adaptation to the environment. The most important advances needed to understand the evolutionary pathways of sleep include wild comparisons to those already conducted in captivity, as well as examining sleep homeostasis in the wild.
Despite increasing interest in the behavior of zoo animals, studies of nocturnal behavior of zoo animals are limited. In this study, we investigated the relationship between parturition, season, and the sleep-related behaviors in captive reticulated giraffes to better understand the nocturnal life in giraffes. The subjects were two adult reticulated giraffes living in Kyoto City Zoo, Japan. Observations were made via an infrared camera that was mounted in the indoor enclosure between June 2007 and August 2009. We analyzed video clips that were recorded between 16:30 and 09:00 the next morning, over a total of 199 days. Sleep-related behaviors were classified into two categories based on the posture of the giraffes; recumbent posture and paradoxical sleep. We also recorded the laterality of recumbent posture, which was coded based on the direction of the legs against the torso (right or left). Seasonal differences in sleep behaviors between summer and winter were observed in both individuals. They tended to start to lie down earlier in the winter than in the summer. Parturition also affected the behaviors as both individuals decreased the behaviors before and after the parturition of the female. Additionally, the female lay on her left side less frequently than her right when resuming a recumbent posture in the pre-parturition period, while such laterality was not observed in the baseline and post-parturition period. These results suggested that season and parturition are important factors for determining the sleep-related behaviors in giraffes. Further studies are needed to understand how these changes in sleep affect other welfare parameters.
The study of sleep in nonmammalian organisms such as insects, birds, and reptiles has revealed many genetic and molecular clues in the understanding of human sleep disorders. Model organisms such as the fruit fly have contributed remarkable insights into our understanding of the mechanisms important to the expression of both normal and abnormal human sleep. Although the cellular and genetic bases for human sleep disorders are not completely understood at the present time, nonmammalian animal studies continue to provide important insights and clues in unraveling the mysteries of sleep. This chapter summarizes the relevant literature from phylogeny which has contributed to our understanding of the genetic, molecular, and environmental factors contributing to the expression of sleep in humans.
Data on sleep, immunity and infection. Species specific values for the time spent in sleep and its different states, the number of white blood cells in peripheral blood, and the degree of parasitism.
Fond as the butterflies are of the light and sun, they dearly love their beds. Like most fashionable people who do nothing, they stay there very late. But their unwillingness to get up in the morning is equalled by their desire to leave the world and its pleasures early and be asleep in good time. They are the first of all our creatures to seek repose. From these charming observations of insect quiescence made more than a century ago to current molecular and genetic studies in the fruit fly, the study of insect sleep during the last decade has evolved into a sophisticated field of inquiry for dis- secting the potential cellular mechanisms controlling sleep in living organisms. The fundamental question of why we sleep continues to be unanswered, but it is likely that sleep in living organisms evolved from ancient origins (Allada & Siegel, 2008; Siegel, 2005). By examining insects, which have a long phylogenetic history, clues to the function and purpose of sleep may be discovered. Sleep in mammalian species such as humans, cats, and rodents has been well studied (Zeplin, Siegel, & Tobler, 2005). In contrast, there are relatively few systematic investigations of nonmammalian vertebrate sleep, and the literature is even sparser for inverte- brate species. Insect sleep, with rare notable exceptions, is almost completely unstudied.
Past research suggests that individuals high in basal testosterone are motivated to gain high status. The present research extends previous work by examining endocrinological and behavioral consequences of high and low status as a function of basal testosterone. The outcome of a competition--victory versus defeat--was used as a marker of status. In Study 1, high testosterone men who lost in a dog agility competition rose in cortisol, whereas high testosterone men who won dropped in cortisol. Low testosterone men's cortisol changes did not depend on whether they had won or lost. Study 2 replicated this pattern of cortisol changes in women who participated in an experimental laboratory competition, and Study 2 extended the cortisol findings to behavior. Specifically, high testosterone winners chose to repeat the competitive task, whereas high testosterone losers chose to avoid it. In contrast, low testosterone winners and losers did not differ in their task preferences. These results provide novel evidence in humans that basal testosterone predicts cortisol reactivity and behavior following changes in social status. Implications for the social endocrinology of dominance are discussed.
Not available Psychology
Limestone hill habitats pose unique challenges to langurs. One of the characteristics of this habitat is its cliffs, which account for about 10-20% of the total area. We have never observed langurs falling from the cliffs during our 10-year field study. Five patterns of locomotion were exhibited by the white-headed langur: (1) arboreal ascent and descent, (2) arboreal quadupedalism, (3) terrestrial quadrupadelism, (4) moving on cliffs and (5) leaping on cliffs. Locomotor patterns varied according to the substrate, but terrestrial quadrupedalism accounted for more than 50% of locomotion time. Moving on cliffs and leaping on cliffs may be modes of locomotion unique to the white-headed langur, at least in terms of frequency. White-headed langurs have an intermembral index of 76 and, compared to langurs with a similar intermembral index, are more terrestrial. Further analysis indicates that greater terrestrialism may be the result of adaptation to their limestone habitat. Interestingly, white-headed langurs select caves on the cliff as their sleeping sites, and they exhibit special behaviors for exiting and entering the cave very early in the morning and late in the evening.
To establish a method for the prolonged recording of electrophysiologic variables of sleep in freely moving nonhuman primates. To establish and validate means for scoring nocturnal sleep and quantifying daytime alertness in these subjects.
Four animals (M. mulatta) were permanently instrumented for the recording of electroencephalograms, electrooculograms, and electromyograms. A telemetry unit housed in a backpack transmitted these variables for several overnight periods to establish normal sleep. During the day, a modified Multiple Sleep Latency Test protocol was followed to quantify daytime alertness. High-quality recordings were maintained from a minimum of 8 months to a maximum of 5.5 years.
Across 6 to 7 nights per animal, average total sleep time was 522 minutes, with a sleep latency of 20 minutes. The proportion of total sleep spent in the various stages of sleep was 10.8%, stage 1; 56.4%, stage 2; 20.0%, stages 3-4; and 12.7%, rapid eye movement sleep. Mean sleep latency across testing sessions for each monkey was 12.5 minutes, 20 minutes (no daytime sleep), 14.6 minutes, and 8.6 minutes for animals 1 to 4, respectively. Intrarater and interrater reliabilities were high and similar to those obtained when the same scorers evaluated human sleep and Multiple Sleep Latency Tests.
Similarities in sleep architecture between M. mulatta and humans make this an excellent animal model for investigations of normal and pathologic human sleep. This study confirms and extends previous findings in nonhuman primates. Stable, high-quality data were obtained for months to years using a telemetric system capable of long-term data collection.
This chapter discusses on the available information on sleep in wild monkeys and apes: like where they sleep, why certain locations might seem favorable or not, with whom the primates sleep, and what they do during the night and early morning. It will be seen that the securing of suitable sleeping sites can be a significant factor in the distribution and behavior of primates and that sleeping habits themselves are modified within overall adaptive patterns of activity. The chapter is intended to help socioecologists formulate questions about sleeping habits and to help sleep researchers, whose theoretical progress has been slowed due to availability of minimum records concerning the sleep of animals in their natural habitat. In captivity, studies of sleep have been largely restricted to physiological investigations, especially electrophysiology. In captivity schedules of food availability are controllable, permitting analysis of this variable on activity profiles including retiring and awakening times. Finally, social interaction is usually easier to monitor in captive primates than in free-ranging ones.
The interrelationships between sleep, ecological, and constitutional variables were assessed statistically for 39 mammalian species. Slow-wave sleep is negatively associated with a factor related to body size, which suggests that large amounts of this sleep phase are disadvantageous in large species. Paradoxical sleep is associated with a factor related to predatory danger, which suggests that large amounts of this sleep phase are disadvantageous in prey species.
Sleeping behavior was investigated during 294 nights for female Asian elephants (circus: n = 7; zoo: n = 5; including an infant). The animals were recorded continuously on time-lapse video tapes for 7-16 days consecutively. Seasonal changes in sleep behavior were studied by comparing summer (16-day) and winter (13-15-day) recordings; and sleep development was assessed by recording a mother and her infant for three consecutive nights per month for 15 months (age 5-19 months). Sleep occurred in a recumbent (RS) and in a standing position (standing sleep: SS). Although signs of paradoxical sleep (PS) were often evident, the exact onset and end of a PS episode could not be determined. Sleep onset occurred after 2100 hours, and sleep increased progressively reaching a maximum between 0100 and 0400 hours. Total sleep time (TST) in the adults comprised 4.0-6.5 hours per night (including 13.8-130.9 minutes of SS) and did not differ between the two groups. Seasonal differences were present in TST and in the distribution of sleep within the night; more sleep occurred in the winter. The duration of RS episodes in the adults was 72.0 minutes, a value far below the sleep-cycle length of 124 minutes that others have reported for elephants. TST in the infant decreased during the course of the 15-month recording period from 8.1 hours to 5.1 hours. SS occurred for the first time at the age of 9 months.
Sleep duration and placement within the twenty-four hour day have been primary indices utilized in the examination of sleep function. It is of value, therefore, to evaluate these variables in a wide range of animal species. The present paper examines the literature concerning sleep duration in over 150 animal species, including invertebrates, fish, amphibians, reptiles, birds, and 14 orders of mammals. We first present annotations of almost 200 studies, including number of animals used, photoperiod employed, sleep duration per twenty-four hours and placement of sleep period within the nychthemeron. Both behavioral and electrographic studies are reviewed, as are laboratory and field studies. These data are subsequently presented in a table with representative literature citations for each species. Following the table, a brief discussion is presented concerning some methodological issues which may affect the measurement of sleep duration and some suggestions are made for future examination of sleep duration.
Behavioural sleep was assessed for 152 nights in 5 adult, 2 immature and 1 juvenile giraffes at a zoological garden, using continuous time-lapse video recording. Sleep occurred while the giraffes were standing (SS) and in recumbency (RS). Paradoxical sleep (PS) was recognized by the peculiar positioning of the head on the croup and by phasic events. The 24-h sleep profile had a main bimodal nocturnal sleep period between 20.00 and 07.00 hours, with a trough between 02.00 and 04.00 hours, and several short naps between 12.00 and 16.00 hours. Total sleep time (TST), excluding the juvenile, was 4.6 h, whereby PS comprised only 4.7%. TST was not age dependent, but the lowest amount of RS and the highest amount of SS occurred in the oldest and the two oldest animals, respectively. Sleep was fragmented, as indicated by the predominance of RS episodes lasting less than 11 min. Sleep cycle duration was very variable with most values between 1 and 35 min (when no waking or RS was allowed within PS episodes), or 6-35 min (when the criteria for ending a PS episode allowed 1-2 min interruptions by RS). There were several indications for sleep regulation: (i) RS and SS complemented each other to yield a relatively stable daily value of TST; (ii) sleep was redistributed on nights following a day when the giraffes spent a few hours in an outside enclosure. The first peak of the bimodal sleep profile was absent and RS was more prominent in the second half of the night compared with nights following days spent in the barn; and (iii) napping was followed by a minor reduction of RS and an increase in SS in the subsequent night compared with nights following days without naps.
Since primates spend about half of their life at sleeping sites, knowledge of behavior in the vicinity of sleeping sites and analysis of factors influencing their use is important for understanding the diversity of primates' adaptations to their environment. The present paper reviews recent progress in the ethology and ecology of sleep in diurnal monkeys and apes. Emphasis is given to the following topics: safety from predators at sleeping sites, physical comfort, social behavior, and psychophysiology of sleep. In all cases, study at the group level and at the individual level can provide insights into behavioral adaptations. As well as increasing understanding of behavior in the wild, knowledge of sleep-related behavior can be applied with a view to improving the environment for captive primates.
Unlabelled:
Falling asleep while driving accounts for a considerable proportion of vehicle accidents under monotonous driving conditions. Many of these accidents are related to work--for example, drivers of lorries, goods vehicles, and company cars. Time of day (circadian) effects are profound, with sleepiness being particularly evident during night shift work, and driving home afterwards. Circadian factors are as important in determining driver sleepiness as is the duration of the drive, but only duration of the drive is built into legislation protecting professional drivers. Older drivers are also vulnerable to sleepiness in the mid-afternoon. Possible pathological causes of driver sleepiness are discussed, but there is little evidence that this factor contributes greatly to the accident statistics. Sleep does not occur spontaneously without warning. Drivers falling asleep are unlikely to recollect having done so, but will be aware of the precursory state of increasing sleepiness; probably reaching a state of fighting off sleep before an accident. Self awareness of sleepiness is a better method for alerting the driver than automatic sleepiness detectors in the vehicle. None of these have been proved to be reliable and most have shortcomings. Putative counter measures to sleepiness, adopted during continued driving (cold air, use of car radio) are only effective for a short time. The only safe counter measure to driver sleepiness, particularly when the driver reaches the stage of fighting sleep, is to stop driving, and--for example, take a 30 minute break encompassing a short (< 15 minute) nap or coffee (about 150 mg caffeine), which are very effective particularly if taken together. Exercise is of little use.
Conclusions:
More education of employers and employees is needed about planning journeys, the dangers of driving while sleepy, and driving at vulnerable times of the day.
Birds and aquatic mammals are the only taxonomic groups known to exhibit unihemispheric slow-wave sleep (USWS). In aquatic mammals, USWS permits sleep and breathing to occur concurrently in water. However, the function of avian USWS has been unclear. Our study is based on the premise that avian USWS serves a predator detection function, since the eye contralateral to the awake hemisphere remains open during USWS. If USWS functions as a form of predator detection, then birds should be able to control both the proportion of slow-wave sleep composed of USWS and the orientation of the open eye in response to changes in predation risk. To test these predictions we recorded eye state and the EEG of mallard ducks (Anas platyrhynchos) sleeping in groups of four birds arranged in a row. Birds at the ends of the row were more exposed than those in the central positions, who were flanked on both sides by other birds, and thus should perceive a greater risk of predation. Consistent with a predator detection function, when compared to birds in the group's center, birds at the exposed ends of the row showed a 150% increase in USWS and a preference for directing the open eye away from the group, the direction from which a predator is most likely to approach. Furthermore, during USWS mallards responded rapidly to threatening visual stimuli presented to the open eye. This ability to facultatively control sleep and wakefulness simultaneously in different regions of the brain probably involves the neuroanatomical interhemispheric separation responsible for independent hemispheric functioning during wakefulness in birds.
Men with low CNS serotonin turnover, as measured by cerebrospinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA) concentrations, exhibit aberrant circadian activity patterns characterized by disrupted sleep rhythms and daytime hyperactivity. To assess whether similar patterns are found in nonhuman primates we examined the relationships between CSF 5-HIAA and nighttime activity in free-ranging monkeys. CSF samples were obtained from 16 adult male rhesus macaques living on a 475 acre, heavily forested sea island. Each subject was captured, fitted with a radio-telemetry motion-detector collar, and then released back into its group. A receiver placed near the sleeping trees of the study subjects recorded activity between 2100 hrs and 0600 hrs. Trained observers recorded behavioral data during the day. The animals followed a typical diurnal activity pattern, as they were active 74% of the sampled time during the day and 37% of the sampled time during the night. CSF 5-HIAA concentrations were inversely correlated with total duration of nighttime activity as well as mean duration of all active events. Nighttime activity was inversely correlated with daytime activity. CSF 3-methoxy-hydroxyphenylglycol (MHPG) concentrations were positively correlated with total nighttime activity, and inversely correlated with daytime sleep frequency. We conclude that male rhesus with low CSF 5-HIAA concentrations have higher total nighttime activity, longer mean periods of nighttime activity, and sleep more during the day than do males with high CSF 5-HIAA concentrations. This suggests that low serotonergic neurotransmission is associated with aberrant diurnal activity, as evidenced by a disruption of nighttime sleep patterns and a compensatory higher rate of inactivity during the day.
Very little is known about the association between sleep and (fatal) occupational accidents. This study investigated this relationship using register data of self-rated sleep difficulties, together with occupational and demographic characteristics. The variables were related to subsequent occupational fatal accidents. A national sample of 47,860 individuals was selected at regular intervals over a period of 20 years, and interviewed over the phone on issues related to work and health. The responses were linked to the cause of death register (suicides excluded) and the data set was subjected to a (multivariate) Cox regression survival analysis. One hundred and sixty six fatal occupational accidents occurred, and the significant predictors were: male vs. female: relative risk (RR)=2.30 with a 95% confidence interval (CI) of 1.56-3.38; difficulties in sleeping (past 2 weeks): RR=1.89 with CI=1.22-2.94; and non-day work: RR=1.63 with CI=1.09-2.45. No significant effect was seen for age, socio-economic group, hectic work, overtime (>50 h per week), or physically strenuous work. It was concluded that self-reported disturbed sleep is a predictor of accidental death at work, in addition to non-day work and male gender.
Aquatic mammals (i.e., Cetaceans, eared seals and manatees) and birds show interhemispheric asymmetries (IA) in slow-wave sleep-related electroencephalographic (EEG) activity, suggesting that the depth of sleep differs between hemispheres. In birds, an association between unilateral eye closure and IA has been reported in five species from three orders (i.e., Galliformes, Charadriiformes, and Anseriformes). Moreover, unilateral eye closure has been observed during behaviorally defined sleep in 29 species from 13 avian orders, suggesting that birds in general display IA during sleep. Despite the apparent prevalence of unilateral eye closure and IA in birds, previous work did not detect IA in the pigeon, thereby challenging the conclusion that this is a general feature of birds. Using digital period amplitude analysis, an objective method for quantifying EEG power (a measure of wave amplitude) across different frequencies, we demonstrate that pigeons do, in fact, display an association between unilateral eye closure and IA. For a given hemisphere, standardized 2-4 Hz EEG power was greater when the contralateral eye was closed when compared to open. We also found that pigeons used the open eye during IA to monitor their environment. In addition, individual pigeons showed a bias for keeping one eye open more than the other. The direction (left vs. right) of this bias differed across birds, and appeared to be influenced by the structure of the surrounding environment. Finally, with the addition of pigeons (order Columbiformes), IA associated with unilateral eye closure has been recorded in four avian orders, suggesting that this form of sleep is widespread in birds.
Falling asleep at work is receiving increasing attention as a cause of work accidents.
To investigate which variables (related to work, lifestyle, or background) are related to the tendency to fall asleep unintentionally, either during work hours, or during leisure time.
5589 individuals (76% response rate) responded to a questionnaire. A multiple logistic regression analysis of the cross sectional data was used to estimate the risk of falling asleep.
The prevalence for falling asleep unintentionally at least once a month was 7.0% during work hours and 23.1% during leisure time. The risk of unintentional sleep at work was related to disturbed sleep, having shift work, and higher socioeconomic group. Being older, being a woman, and being a smoker were associated with a reduced risk of unintentionally falling asleep at work. Work demands, decision latitude at work, physical load, sedentary work, solitary work, extra work, and overtime work were not related to falling asleep at work. Removing "disturbed sleep" as a predictor did not change the odds ratios of the other predictors in any significant way. With respect to falling asleep during leisure time, disturbed sleep, snoring, high work demands, being a smoker, not exercising, and higher age (>45 years) became risk indicators.
The risk of involuntary sleep at work is increased in connection with disturbed sleep but also with night work, socioeconomic group, low age, being a male, and being a non-smoker.
Several aspects of behaviour relating to sleep in monkeys and apes are reviewed, including sleeping site selection, approach to and departure from sleeping sites, social behaviour at the sites, and nocturnal activities. Illustrative examples are given for each topic. Good sleeping sites for primates give protection from predators and/or some physical comfort from the elements and other sources of disturbance. Availability of sleeping sites may determine ranging patterns and whether an area is exploited or not. Times of retiring and resumption of daytime activities are influenced by foraging and ranging requirements. Social relationships and their influencing factors continue during the night, including dominance, kinship, affiliation and sex. Social partners may be used for thermoregulation and for increasing postural stability. Primates show a range of solutions to the problems surrounding sleep, and similarities and differences between monkeys and the large-bodied, nest-building great apes are described. Knowledge of natural sleep-related phenomena in non-human primates can provide valuable insights for human sleep research, and vice-versa.
This authoritative guide to sleep medicine is also available as an e-dition, book (ISBN: 1416003207) plus updated online reference! The new edition of this definitive resource has been completely revised and updated to provide all of the latest scientific and clinical advances. Drs. Kryger, Roth, and Dementand over 170 international expertsdiscuss the most recent data, management guidelines, and treatments for a full range of sleep problems. Representing a wide variety of specialties, including pulmonary, neurology, psychiatry, cardiology, internal medicine, otolaryngology, and primary care, this whos who of experts delivers the most compelling, readable, and scientifically accurate source of sleep medicine available today. Includes user-friendly synopses of important background information before all basic science chapters. Provides expert coverage of narcolepsy * movement disorders * breathing disorders * gastrointestinal problems * neurological conditions * psychiatric disturbances * substance abuse * and more. Discusses hot topics such as the genetic mechanisms of circadian rhythms * the relationship between obesity, hormones, and sleep apnea * sleep apnea and arterial hypertension * and more. Includes a new section on Cardiovascular Disorders that examines the links between sleep breathing disorders and cardiovascular abnormalities, as well as the use of sleep related therapies for congestive heart failure. Provides a new section on Womens Health and Sleep Disorders that includes information on the effects of hormonal changes during pregnancy and menopause on sleep. Features the fresh perspectives of 4 new section editors. Employs a more consistent chapter organization for better readability and easier navigation.
Video-films, recorded continuously, of a captive group of spot-nosed monkeys (Cercopithecus petaurista) were analysed with special respect to the behavior exhibited by newborn monkeys during the night. Nocturnal room illumination was consistently 0·5 lux. Particular action patterns could be distinguished. Until the 11th night, social interactions were restricted by the mother maintaining close bodily contact with the infant. Both frequency and duration of infants nocturnal motility periods showed a maximum value during their first night, and decreased later on. Analysis of the temporal ordering of particular action patterns provided evidence for regular recurrence cycles which could be explained by ultradian periodicities (cycle lengths: 10 s, 60 min., two and four hours).
There are reasons to consider incomplete the description of sleep in many non-human primate species. Recording animals by highly sensitive videos to obtain detailed descriptions of nighttime behavior and evidence of muscle activity while in a resting posture, seems a promising approach to the non-invasive study of sleep in non-human primates. The present work describes the use of ultrasensitive videocameras to record and analyze spontaneous nighttime behaviors in captive non-human primates. Its main purpose is to emphasize the utility of videorecordings to analyze nighttime behavior. A heterosexual group of nine stumptail macaques (M. arctoides) was studied. It was possible to identify resting postures: immobility or lying on the floor as well as sleep movements and behavioral signs of sleep. This procedure permits recognition of each animal individually and the data suggest that videorecordings, among other techniques available, may be a useful, non-invasive method to study sleep. © 1995 Wiley-Liss, Inc.
Measures of all night sleep physiology (EEG, EOG, EMG, heart rate (HR), body temperature (BT)) were recorded from 8 totally unrestrained infant M. nemestrina monkeys (mean age 26.1 weeks) for a total of 31 nights. Objective measurements of daytime behaviors were obtained in 7 of the infants. Mean sleep latency for the group was 35 min; individual sleep latency was related to maternal dominance. Mean total sleep time was 558 min, and mean sleep stage values for the group were drowsy, 16 min, Stage 2, 302 min, Stage 3–4, 150 min, and REM, 90 min. Mean interREM interval was 59.2 min. Infants exhibiting more locomotive behavior also had more Stage 3–4 sleep. Lower HR values were often found during deep slow wave sleep, but most nocturnal HR and BT variability did not appear closely associated with sleep patterns per se. Higher nocturnal body temperature and heart rate values were found in those infants engaging in greater amounts of play behavior and receiving more punishment from adults. Our findings are considered in terms of developing a biobehavioral developmental profile for the monkey infant.
The sleep pattern of sixteen baboons (Papio papio) was studied under two very different conditions: (1) in a laboratory at Marseilles, the monkey being immobilized in a restraining chair in a soundproof cubicle; (2) in an African reserve, the monkey being housed in a large cage placed in its natural environment. Some very marked differences emerged. Sleep in the laboratory was longer (by 24 min) and richer in stage 3 and paradoxical sleep. In Africa, however, the sleep showed much more stage 1, was more fragmented and stages 2 and 3 and paradoxical sleep episodes were of shorter duration. Records made in Africa indicate that sleep is independent of slight environmental changes (day length, brightness of the moon, variations in temperature, calls of predators). But the comparison of the two series of results reveals the reorganization which occurs when the monkey is exposed to such different conditions. This adaptation to the environment affects, unequally, the various slow sleep stages and paradoxical sleep. In fact, the major modifications occur in stages 1 and 3 of slow sleep and in paradoxical sleep, while stage 2 appears to constitute the stable, unmodifiable nucleus of sleep.
A systematic study was made of several nonhuman primates to learn more about their relative usefulness for studies of sleep. Species studied included the Guinea baboon (Papio papio), Kenya or yellow baboon (P cynocephalus), olive baboon (P anubis), sacred baboon (P hamadryas), vervet monkey (Cercopithecus aethiops), rhesus monkey (Macaca mulatta), bonnet monkey (M radiata), crab-eating monkey (M fascicularis), patas monkey (Erythrocebus patas), chimpanzee (Pan troglodytes), mongoose lemur (Lemur mongoz), black lemur (Lemur macaco fulvus), and bushbaby (Galago senegalensis). Comparisons were made of electroencephalographic activity, states of vigilance, and responses to sleep-waking drugs. The results showed that there were major similarities among the genera studied as well as individual intrageneric and intraspecies differences. It was concluded that the chimpanzee, olive baboon, and rhesus monkey were the best species for comparative studies, and that the rhesus monkey was the best single model because of its well defined sleep organization and ease of handling and housing.
Over a one year period, 14 and 24 h EEG records were obtained with scalp electrodes from 14 infant chimpanzees aged from 2 to 41 months, sleeping on a couch in a soundproof room. They started to crawl at 3 months, sit and stand at 4-5 months, walk at 6-7 months, climb at 8-9 months and run and swing around 15 months. They napped until 9-10 months. The EEG morphology changed constantly until 2-3 years. Each stage had its own individual evolution. The waking EEG was composed of low voltage fast activity. Alpha rhythm appeared at 3 months, increased in amplitude until 20 months and became well stabilized around 30-36 months. Drowsiness with EEG hypersynchrony was seen at 11 months, the hypersynchrony became maximal in amplitude and duration at 18 months and then decreased. Stage 1 increased with age in number of occurrences, duration and EEG frequency. Sharp wave activity was seen in the parieto-occipital areas after 2 months and then increased in incidence and amplitude until around 18 months after which it declined and was rarely seen again. In stage 2 spindles declined in amplitude, occurrence and frequency with age, unlike the V waves and K complexes which increased in occurrence and definition with age. Stage 3 had few spindles, but more K complexes. High voltage sharp waves at 4-5 c/sec occurred in bursts between 1 and 2 years and then disappeared. Slow waves in the delta band marked the pattern of stage 3 after 2 years. Stage 4 was not seen before 4-5 months. High voltage sharp waves were maximal in amplitude and occurrence around 18 months. Delta activity was synchronous and without overriding faster activity after 2 years. REM showed an increase in frequency of background activity with age but decrease in percentage along with decreases in centro-parietal spike activity. The EEG pattern tended to reach maturity around 3 years.
EEG records were taken from three newborn chimpanzees up to the age of 2 months. Both 24 h and day time records were made with the animals lying unrestrained in an Isolette incubator. Some records were telemetered, using a 3-channel Signatron Transmitter Unit. In the first day of life the slow sleep dominant pattern was one of low voltage theta activity interrupted by bursts of slower frequencies. Poorly defined spindles were frequently observed but rapid eye movement (REM) was difficult to identify. At 2 days the slow sleep pattern had disappeared and slow waves (2-4 c/sec) and theta activity often dominated the REM pattern. Well defined REM sometimes closely resembled the record of open-eyed waking. The amplitude of the record increased linearly with age and spindles (14-15 c/sec) developed completely. Stage 3 occurred more frequently with longer duration but no stage 4 was observed. Centro-occipital positive sharp waves were seen during REM at around 2 months. On the other hand, stage 2 also showed sharp waves in the parieto-occipital region but with an inverse polarity to those observed during REM. The ontogeny of the chimpanzee EEG was similar to that of man in some respects but seemed more closely akin to that of the lower primates.
The nocturnal distribution and behavior of individually marked Macaca mulatta were studied at the La Parguera, Puerto Rico, colony of the Caribbean Primate Research Center. The new image intensifier was used successfully to identify 399 monkeys in 185 sleeping clusters. Monkeys moved into mangrove trees close to favorite feeding areas usually 35 minutes after sunset. The group condensed to less than one-half the daytime spread, vocalizations increased and grooming ceased. Movements and vocalizations ceased several hours after sunset, although bursts of activity occurred throughout the night. Activity resumed 40 minutes before sunrise. Activity was higher during full moon, when I observed feeding, play and sexual behavior. Fights at night were twice as frequent during the breeding season. Monkeys slept in clusters of one to four, 58% of which were of two. Sixty-three percent were composed of maternal relatives, 33% were mother-infant pairs. Mature males clustered with non-related males, slept alone or with females (in the breeding season). Yearlings slept with their mothers or with older siblings. Distribution of monkeys in a group at night reflects daytime associations.
The behavior of rhesus monkeys (Macaca mulatta) was observed via videotape recording during the 12 hour period from 6.00 p.m. to 6.00 a.m. Adult animals were housed in male/female pairs under one of three cage conditions: individual cage, mating cage and a larger 'group' cage. 20 categories of behavior were assessed and the resultant behavior was described and quantitatively compared across cage conditions. The animals spent almost the entire night in a sitting position, either alone or while huddling with another animal. Sitting and huddling behavior are near-perfect complements to each other in terms of the frequency of occurrence; taken together they account for almost the entire nocturnal behavior. Other activity rarely displaces these behaviors. The animals tended to be relatively active in the early evening. As night fell, they settled down to relative inactivity, which they maintained until the morning. The activity level gradually increased as dawn approached.
An avenue to investigate the functions of sleep is the comparison of sleep in different species, particularly in closely related ones and in species with extreme specializations. The features which are usually investigated are the occurrence of both sleep stages non-REM sleep and REM sleep, their amount per 24 h, the duration of the non-REM-REM sleep cycle and the daily distribution of sleep relative to the light-dark cycle of the environment. Recently also sleep homeostasis has been included, because it is now well established that mammalian species can compensate for sleep loss both by an increase in sleep duration as well as by intensifying non-REM sleep. The occurrence of EEG slow-wave activity has served as a measure for sleep intensity. The capacity to sleep more intensely enables animals to react more flexibly to sleep loss. The comparison of mammalian species has revealed striking similarities in the way sleep is regulated which indicates common underlying mechanisms.
Extensive work on sleep-wake cycles in non-human primates has been carried out using conventional EEG scoring. In this study, simultaneous somnopolygrams and video recordings at 1 frame/s were performed on 6 adult rhesus monkeys (Macaca mulatta) during a 24 h period. Wakefulness, NREM sleep and REM sleep were scored by analysis of animal behavior from video data, using characteristic criteria for each state of vigilance. Results were then compared with those of conventional EEG scoring. Values of the total amount for each state obtained by the two scoring methods during the light and the dark periods were significantly closely related (P < 0.001) with a high correlation coefficient for wakefulness (r1 = 0.99956), for NREM sleep (r1 = 0.99641) and for REM sleep (r1 = 0.98708). Moreover, the epoch by epoch analysis between both methods showed a high concordance with percent agreement values of 95.68% for wakefulness, 93.52% for NREM sleep and 94.02% for REM sleep. The number of REM sleep episodes was similarly defined. The patterns of successive sleep-wake cycles determined from both scorings were superimposable, as were the frequent state changes for the same time segments. The video method's main limitation was that the 4 stages of NREM sleep could not be differentiated. Reliability and advantages of sleep-wake scoring by behavioral analysis are discussed. These results suggest that the video methodology is relevant as a non-invasive technique complementary to conventional EEG analysis for sleep studies in rhesus monkeys.
Although it has been well documented that sleep is required for human performance and alertness to recover from low levels after prolonged periods of wakefulness, it remains unclear whether they increase in a linear or asymptotic manner during sleep. It has been postulated that there is a relation between the rate of improvement in neurobehavioral functioning and rate of decline of slow-wave sleep and/or slow-wave activity (SWS/SWA) during sleep, but this has not been verified. Thus, a cross-study comparison was conducted in which dose-response curves (DRCs) were constructed for Stanford Sleepiness Scale (SSS) and Psychomotor Vigilance Task (PVT) tests taken at 1000 hours by subjects who had been allowed to sleep 0 hours, 2 hours, 5 hours or 8 hours the previous night. We found that the DRCs to each PVT metric improved in a saturating exponential manner, with recovery rates that were similar [time constant (T) approximately 2.14 hours] for all the metrics. This recovery rate was slightly faster than, though not statistically significantly different from, the reported rate of SWS/SWA decline (T approximately 2.7 hours). The DRC to the SSS improved much more slowly than psychomotor vigilance, so that it could be fit equally well by a linear function (slope = -0.26) or a saturating exponential function (T = 9.09 hours). We conclude that although SWS/SWA, subjective alertness, and a wide variety of psychomotor vigilance metrics may all change asymptotically during sleep, it remains to be determined whether the underlying physiologic processes governing their expression are different.
Transition to adulthood
- J R Walters
- B B Smuts
- D L Cheney
- R M Seyfarth
- R W Wragham
- T T Struhsaker
Walters JR. Transition to adulthood. In: Smuts BB, Cheney DL, Seyfarth RM, Wragham RW, Struhsaker TT, editors. Primate societies.
Chicago: University of Chicago Press; 1987. p. 358-69.
Social aspects of sleep cluster formation and sleep behaviour in a mixed group of longtailed macaques (Macaca fascicularis)
- L Gygax
- I Tobler
Gygax L, Tobler I. Social aspects of sleep cluster formation and
sleep behaviour in a mixed group of longtailed macaques (Macaca
fascicularis). Available on: http://www.proximate-biology.ch/downl/
manu.html, 2001.
Sleep ontogeny in the chimpanzee: from 2 months to 41 months
- Balzamo
Balzamo E, Bradley RJ, Rhodes JM. Sleep ontogeny in the chim-panzee: from 2 months to 41 months. Electroencephalogr Clin Neu-rophysiol 1972;33(1):47–60.
Etude des états de vigilance chez Papio cynocephalus adulte
- Balzamo
Mammalian sleep in principles and practice of sleep medicine
- H Zepelin