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(A) Changes in core body temperature during sleep with HR and LR in old adult males (study II). As observed in younger subjects (Fig 2), larger decline in core body temperature (CBT) was observed with HR between 23:00-03:00 in old subjects (p<0.01 by topper type, p<0.02 by time, p<0.01 by topper type x time, repeated measures ANOVA with grouping factor). (B) EEG delta power changes across the night (study II). Larger delta-power was observed with HR between 23:00-03:00 (p<0.01 by topper type, p = 0.23 by time, p<0.05 by topper type x time, repeated measures ANOVA with grouping factor). 

(A) Changes in core body temperature during sleep with HR and LR in old adult males (study II). As observed in younger subjects (Fig 2), larger decline in core body temperature (CBT) was observed with HR between 23:00-03:00 in old subjects (p<0.01 by topper type, p<0.02 by time, p<0.01 by topper type x time, repeated measures ANOVA with grouping factor). (B) EEG delta power changes across the night (study II). Larger delta-power was observed with HR between 23:00-03:00 (p<0.01 by topper type, p = 0.23 by time, p<0.05 by topper type x time, repeated measures ANOVA with grouping factor). 

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Article
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Recently, several new materials for mattresses have been introduced. Although some of these, such as low rebound (pressure-absorbing/memory foam) and high rebound mattresses have fairly different characteristics, effects of these mattresses on sleep have never been scientifically evaluated. In the current study, we have evaluated effects of a high...

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... An inappropriate sleep environment results in di culty falling asleep and affects nap quality and recovery from fatigue, and subsequent sleepiness [7,12]. Several studies have scienti cally assessed the effect of bedding on nocturnal sleep and physiological variables during sleep [13][14][15]: a few studies have demonstrated the relationship between suitable napping and associated environmental factors. Zhao et al. showed that napping in a chair with the trunk tilted forward 45 degrees and the head resting on a special pillow was not signi cantly different from a nap in a bed in terms of objective sleep variables; however, compared with those with no nap, subjective sleepiness and fatigue improved in both the chair and bed [16]. ...
... As this study was limited to a short nap experiment not encompassing a whole night's sleep, signi cant differences in sleep architecture were di cult to obtain for each bedding condition. Even previous studies exploring the effect of high resistance bedding on all-night sleep revealed no statistical differences in sleep architecture, only an increase in delta power in the rst cycle of non-REM sleep [15]. Moreover, admitting that napping is a style of incomplete sleep, represented by the fact that most participants showed no signs of slow-wave sleep or REM sleep, the lack of signi cant differences in the quantitative frequency analysis is quite consistent with sleep propensities. ...
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Although ample evidence has demonstrated that daytime napping is beneficial for health and cognitive performance, bedding for napping has not yet been scientifically investigated. In this study, we assessed the effect of a bean bag chair (BC), which would automatically adjust according to body shape and size, on daytime napping and physiological parameters related to sleep, such as electroencephalogram (EEG), electromyogram (EMG), and heart rate variability (HRV). Fourteen healthy participants were enrolled within the context of a randomized, single-blind, crossover study to evaluate the effects of a BC in comparison with those of a urethane chair manufactured to have a similar shape (UR). EEG analyses revealed no significant differences in sleep architecture or frequency components; however, a significant decrease was found in EMG recordings in the trapezius muscle, which represents the neck region (p = 0.024). Additionally, a significant main effect of bedding in the LF/RF ratio (F [1, 20] = 4.314, p = 0.037) was revealed. These results suggest that napping with a BC may provide a comfortable napping environment involving muscle relaxation and proper regulation of autonomic nervous function.
... This difference in HR was observed across the night when participants slept on the HHCM compared to the LHCM As has been previously reported 28,29 the temperature of this HHCM was significantly lower than the control LHCM, with the largest differences being in the first 5 hours of the 8-hour sleep opportunity. Differences in cBT temperature were observed starting 90 minutes after lights out, which was also similar to the change in cBT in middle aged men [27][28][29] . Specifically, cBT was lower and remained lower on the HHCM than on the LHCM for the remainder of the sleep period. ...
... Interestingly there was no significant difference in distal temperature. While the present study in post-menopausal women more or less confirms the results of the recent publications in younger men [27][28][29] , interpretation of the differences is challenging and speculative, without a study directly comparing the different age groups in both genders. ...
... This supports the idea that the lower cBT in the first part of the sleep period is important for the distribution of key homeostatic markers across the sleep period 39 . Similar findings in young and older men using just a mattress topper 27 indicate that sleep on the high rebound topper resulted in a reduction in cBT in the first part of the night paralleling an increase in delta power in the first few hours of sleep, compared to the control topper. The consistency of the finding between all of these studies [27][28][29] suggest that manipulation of body temperatures by altering the sleeping surface may be a useful tool for improving sleep in both men and women of various ages. ...
Article
Study Objectives A decline in sleep quality, slow wave sleep (SWS) and slow wave activity (SWA) are common in older adults. Prior studies have shown that manipulating body temperature during sleep can increase SWS/SWA. The aim of this study was to determine the effects of manipulation of body temperatures during sleep, using a high heat capacity mattress, on SWS/SWA and heart rate in post-menopausal women. Methods Twenty-four healthy postmenopausal women between 40-75 years of age (mean age 62.4 ± 8.2 years, mean BMI 25.4 ± 3.5 kg/m²) were randomized in a single-blind, counterbalanced, cross-over manner to sleep on either a high heat capacity mattress (HHCM) or a low heat capacity mattress (LHCM) a week apart. Sleep was recorded using polysomnography during an 8-hour sleep opportunity. Core and peripheral temperature were recorded using an ingestible capsule and thermochron respectively. Results In comparison to the LHCM, sleep on HHCM exhibited a selective increase in SWS (average increase in Stage N3 of 9.6 minutes (2.1%), p = 0.04) and in slow oscillatory (SO) activity (0.5-1Hz) in the first NREM/REM cycle (p=0.04). In addition, the HHCM induced a greater reduction in core body temperature (p=0.002). The reduction in core body temperature (first 180 minutes after lights out) from LHCM to HHCM was associated (r=0.5, p=0.012) with the increase in SO activity (SO cycle 1 and 2/cycle 3 and 4). Average heart rate was 1.6 beats/minute lower across the night on the HHCM compared to the LHCM (p=0.001). Conclusions The results of this study indicate that manipulation of body temperature during sleep may be a useful approach to enhance SWS sleep in postmenopausal women.
... Mattresses with various types of materials are commercially available and have fairly different characteristics. The limited amount of research present on the effects of sleep surfaces on sleep have shown that sleep surfaces affect sleep in various ways [12][13][14] . ...
... In fact, we have recently demonstrated that high rebound (HR) mattress toppers induce a continuous and more rapid decline in core body temperature during the initial phase of nocturnal sleep compared to low rebound (LR) mattress toppers in young healthy males 13 . We refer to a type of polyethylene resin fiber-based mattress that has a firm, supportive feel as HR and memory foam mattresses as LR. ...
... We refer to a type of polyethylene resin fiber-based mattress that has a firm, supportive feel as HR and memory foam mattresses as LR. Polysomnographic evaluations (PSG) showed that an increase in the amount of deep sleep and a predominance of parasympathetic nerve activity occurs in association with the changes in core body temperature 13 . These results suggest that effective heat loss occurs while subjects sleep on HR mattress toppers, and this heat loss may facilitate the occurrence of deeper sleep. ...
Article
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We recently demonstrated that sleeping on high rebound [HR] mattress toppers induced a continuous and more rapid decline in core body temperature compared to low rebound [LR] mattress toppers during the initial phase of nocturnal sleep in young healthy volunteers. HR toppers are characterized by their supportive feel and high breathability whereas LR toppers are pressure-absorbing. In the current study, we evaluated effects of HR mattress toppers on objectively-(actigraphy) and subjectively-(questionnaires) evaluated sleep, vigilance (psychomotor vigilance test), and athletic performance (40-m sprint time, long jump distance, and star drill time) in youth male athletes age 10–19, in two sessions: fifty-one subjects in 2013 (study I) and 23 subjects in 2014 (study II). Sleeping on HR mattress toppers for four to six weeks improved some athletic performance measures compared to sleeping on LR or sleeping directly on spring mattresses without a topper. Statistically significant improvements in 40-m sprint time in study I (compared to LR) and in star drill time in study II (no topper) were observed. No changes in sleep and psychomotor vigilance were observed. These results suggest selecting optimal sleep surfaces may contribute to the maximization of athletic performances, and further studies are warranted.
... Thus, the characteristics of a mattress topper would become the main factors influencing sleeping comfort, owing to the user's body contacts with the topper directly. To investigate the effects of mattress toppers, Chiba et al. (2018) evaluated the effects of mattress topper materials (high rebound and low rebound) on body temperature, EMG, and subjective ratings and reported that the high rebound mattress toppers would facilitate a core body temperature drop and enhance deep sleep in the initial phase of nocturnal sleep. Wong et al. (2019) suggested that the better combination of bed system cannot yet be justified in view of the lack of sufficient evidence. ...
... A rest period of 5 min was given after each successful MVC measurement. The measuring procedures and postures of the four muscles were similar to the study of Chiba et al. (2018) and Lahm and Iaizzo (2002). ...
... A proper sleeping system should have the characteristics of (1) minimizing and distributing body pressures, (2) maintaining a straight spine, (3) avoiding muscle fatigue, and (4) maintaining a suitable body temperature (Chiba et al., 2018;Califano et al., 2017;Chen et al., 2014;Verhaert et al., 2013). In this study, the topper thickness and hardness effects on the body pressure distribution, body temperature, EMG, and spinal alignment were evaluated. ...
Article
Placing a topper on a sleeping system is common practice to enhance sleeping comfort. The aim of this study was to determine the thickness and hardness effect of a mattress topper by measuring the four physiological measurements from 40 healthy males. The results showed that the use of a thin mattress topper (30 mm) significantly induced lower body pressure and temperature, higher muscle activities in the biceps femoris, and a straighter spinal alignment in the T12–L4 vertebrae. The use of a hard mattress topper significantly induced a higher body pressure, a lower body temperature in the lower extremities, a higher EMG (%MVC) in the trapezius, but a lower EMG (%MVC) in the biceps femoris, and a straighter spinal alignment at T1–T4, T4–T6, and T6–T8. Overall, a soft topper of 30-mm thickness was suggested as the best combination. The findings can provide very useful information for topper design and selection.
... Earlier research in this field attempting to influence CBT during sleep by manipulation of environmental thermal influence factors, for example ambient air temperature (AIRT), was limited because the application of the intervention can disturb sleep and cause adverse reactions [2,6,16]. It was found that such interventions require remaining within a thermal comfort zone of ambient AIRT to avoid disturbing regular sleep [17,18]. Kräuchi et al. recently investigated the effect of a high-heat capacity mattress (HM) as an example of a reliable thermal intervention on sleep in healthy young men [1]. ...
... Hz (N = 13 frequency bins). Based on previous findings [17,18,22], standardized EEG energy in the delta-band (=standardized slow wave energy, sSWE) was considered as the primary spectral measure for this study. To illustrate this with a hypothetical example, if all sleep epochs in the second half of the night would be rated as NREM sleep, and the entire EEG energy would be located in the delta range (0.781-4.297 ...
... Time course analyses showed only small non-significant differences in sleep stage N3/10 min-intervals, however, accumulated over time, they amounted to significant increases in N3 at the end of the night in HM compared with LM (see Figure 2). In a very recent study, similar results were found in a comparison of two different mattress types (different materials than HM and LM) inducing different decline patterns in CBT and HR [18]. Unfortunately, no skin temperatures were recorded, which precludes a direct comparison with the present study. ...
Article
Study Objectives This study deals with the question whether a slow (non-disturbing) reduction of core body temperature (CBT) during sleep increases sleep stage N3 and EEG slow wave energy (SWE) and leads to a slowing of heart rate in humans. Methods A high-heat capacity mattress was used to lower body temperatures in sleep and was compared to a conventional low-heat capacity mattress in a double-blinded fashion. Polysomnography was performed accompanied by measurements of skin-, core body- and mattress surface-temperatures, and heart rate. EEG power spectral analyses were carried out using Fast Fourier Transform. Inter-beat intervals were derived from the electrocardiogram. Results The high-heat capacity mattress led to a larger decline in CBT, mediated through higher heat conduction from the core via the proximal back skin onto the mattress together with reduced heart rate. These effects occurred together with a significant increase in sleep stage N3 and standardized slow wave energy (sSWE, 0.791-4.297Hz) accumulated in NREM sleep. In the 2nd half of the night sSWE increase was significantly correlated with body temperature changes, e.g. with CBT decline in the same phase. Conclusions A high-heat capacity mattress subtly decreases CBT, leading to an increased amount of sleep stage N3 and of sSWE, as well as a slowing of heart rate.
Article
Full-text available
Background Although ample evidence has demonstrated that daytime napping is beneficial for health and cognitive performance, bedding for napping has not yet been scientifically investigated. Objectives To explore the effect of a bean bag chair on daytime napping and physiological parameters related to sleep. Methods Fourteen healthy participants were enrolled within the context of a randomized, single-blind, crossover study to evaluate the effects of a bean bag chair in comparison with those of a urethane chair manufactured to have a similar shape. Electroencephalogram, electromyogram, and heart rate variability were recorded and compared between wakefulness and napping. Results Electroencephalogram analyses revealed no significant differences in sleep architecture or frequency components; however, a significant decrease was found in electromyogram recordings in the trapezius muscle, which represents the neck region ( p = 0.019). Additionally, a significant main effect of bedding in the low-frequency/high-frequency ratio ( F [1,20] = 4.314, p = 0.037) was revealed. Conclusions These results suggest that napping in a bean bag chair may provide a comfortable napping environment involving muscle relaxation and proper regulation of the autonomic nervous function.