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ABSTRACT: Previous neuroimaging studies that examined cerebral blood flow during rapid eye movement (REM) sleep have reported inconsistent findings regarding the activity of the dorsolateral prefrontal cortex (DLPFC). Although most previous positron emission tomography (PET) studies failed to detect DLPFC activation during REM sleep, several studies have observed DLPFC activation, possibly reflecting transient prefrontal activities related to REM. More recently, an event-related functional magnetic resonance imaging (fMRI) study observed REM-locked activation of the DLPFC during REM sleep. The present study investigated hemodynamic changes of the DLPFC throughout the REM sleep period in 25 subjects using near-infrared spectroscopy. Continuous monitoring of changes in the hemoglobin (Hb) concentration and tissue oxygenation index (TOI, proportion of oxygenated-Hb to total-Hb) in the bilateral DLPFC was conducted every 0.5s, simultaneously with polysomnographic recordings. Eight of the 25 subjects showed REM sleep, and all indicated a clear increase in both the oxygenated-Hb concentration and TOI from baseline at the occurrence of first REM, relative to prior stage 2 sleep. The results indicate that the appearance of the first REM that occurred just after onset of the REM sleep closely coincides with the activation of the DLPFC, which could play a role in cognitive activities during REM sleep in humans.
Brain research 03/2011; 1389:83-92. · 2.46 Impact Factor
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ABSTRACT: This study aimed at elucidating the physiological significance of dusk and dawn in the circadian rhythm of core temperature (T(core)) and urinary 6-hydroxymelatonin sulfate in humans during sleep and the waking sensation just after rising. Seven female and four male students served as participants. Participants retired at 2300 h and rose at 0700 h. They were requested to sit on a chair and spend time as quietly as possible during wakefulness, reading a book or listening to recorded light music. Two lighting conditions were provided for each participant: 1) Light-Dark (LD)-rectangular light change with abrupt decrease from 3,000 lx to 100 lx at 1800 h, abrupt increase from 0 lx to 3,000 lx at 0700 h. 2) LD-twilight light change with gradual decrease from 3,000 lx to 100 lx starting at 1700 h (twilight period about 2 h), with gradual increase from 0 lx to 3,000 lx starting at 0500 h (twilight period about 2 h). The periods of 0 lx at night were from 2300 h to 0700 h on the first day and from 2300 to 0500 h on the second day. Nadir time advanced significantly under the influence of the LD-twilight condition. The amount of 6-hydroxymelatonin sulfate in urine collected at 0200 h was significantly higher under LD-twilight in comparison with LD-rectangular light. Morning drowsiness tended to be lower under LD-twilight. Our results suggest that in architectural design of indoor illumination it is important to provide LD-twilight in the evening and early morning for sleep promotion in healthy normal people and/or light treatment in elderly patients with advanced dementia.
Collegium antropologicum 04/2009; 33(1):193-9. · 0.61 Impact Factor
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ABSTRACT: The experiment investigated the effect of light wavelength upon salivary secretion and cutaneous temperature of the foot in humans. Seven healthy young female students served as participants. They spent three nights in a bioclimatic chamber controlled at 26 degrees C and 60%. Participants were exposed to two different wavelengths of light from 1800 to 2400 h on second day and third day: 1) Fluorescent light (FL) with short wavelengths and a high color temperature (6,500 K); 2) Incandescent light (IL) with long wavelengths and a low color temperature (3,000 K). Light intensity was 400 lx in both conditions. Saliva was collected every 10 min from 2100 to 2200 h, and from 2300 to 2400 h on the second and third days, by a Lashley cup fixed to the parotid gland. The mean salivary secretion rate between 2100 and 2200 h was 15.27 +/- 2.86 g/h (Mean +/- SEM, N = 7) in the IL condition and 10.80 +/- 2.97 g/h in the FL condition (p < 0.011) and, between 2300 and 2400 h, 14.98 +/- 3.80 g/h in the IL condition and 11.55 +/- 2.60 g/h in the FL condition (p < 0.057). Foot skin temperature was significantly higher in IL than FL during the period 1800-2400 h. These findings suggest that the parasympathetic nervous system, which is responsible for serous saliva flow, is less suppressed by IL condition, and that the sympathetic nervous system, which is responsible for vasoconstriction of foot skin vessels, is less activated by IL.
Collegium antropologicum 01/2008; 31(4):969-72. · 0.61 Impact Factor
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ABSTRACT: The present experiment aimed at knowing how a gradual changes of room temperature (T(a)) and light in the evening and early morning could influence circadian rhythms of core temperature (T(core)), skin temperatures, urinary 6-hydroxymelatonin sulfate and waking sensation just after rising in humans. Two kinds of room environment were provided for each participant: 1) Constant room temperature (T(a)) of 27 degrees C over the 24 h and LD-rectangular light change with abrupt decreasing from 3,000 lx to 100 lx at 1800, abrupt increasing from 0 lx to 3,000 lx at 0700. 2) Cyclic changes of T(a) and with gradual decrease from 3,000 lx to 100 lx onset at 1700 (twilight period about 2 h), with gradual increasing from 0 lx to 3,000 lx onset at 0500 (about 2 h). Main results are summarized as follows: 1) Circadian rhythms of nadir in the core temperature (T(core)) significantly advanced earlier under the influence of gradual changes of T(a) and light than no gradual changes of T(a) and light. 2) Nocturnal fall of T(core) and morning rise of T(core) were greater and quicker, respectively, under the influence of gradual changes of T(a) and light than no gradual changes of T(a) and light. 3) Urinary 6-hydroxymelatonin sulfate during nocturnal sleep was significantly greater under the influence of gradual changes of T(a) and light. 4) Waking sensation just after rising was significantly better under the influence of gradual changes of T(a) and light. We discussed these findings in terms of circadian and thermoregulatory physiology.
Collegium antropologicum 07/2007; 31(2):587-93. · 0.61 Impact Factor
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ABSTRACT: The present study investigated whether room temperature (T(a)) cycles around dusk and dawn could influence the circadian rhythm of rectal temperature (T(core)), urinary 6-hydroxymelatonin sulfate during nocturnal sleep, and subjective assessments of sleep in humans. Six female and two male students served as participants. Two different T(a) conditions, cyclic and constant, were established. Two kinds of room temperature were provided to subjects: cyclic T(a) (gradual decrease from 27 degrees C to 24 degrees C between 1800 and 2200 h and gradual increase from 24 degrees C to 27 degrees C between 0300 and 0700 h) and constant T(a) (27 degrees C over 24 h). At cyclic T(a), the circadian nadir of T(core) rhythm was significantly advanced, while T(core) was significantly lower from 2300 to 0200 h and significantly higher from 0600 to 1000 h. The nocturnal concentration of 6-hydroxymelatonin sulfate in the urine during sleep was significantly higher during cyclic T(a). Waking sensation just after rising was significantly better with cyclic T(a). (Skin temperatures in the extremities-T(a)) were significantly higher with cyclic T(a) especially during the evening and night. Our results suggest that gradual change of room temperature in the evening and early morning is important in terms of sleep promotion and fresh awakening. It seems probable that mankind has been evolved to have deeper sleep under the influence of cyclic T(a) around dusk and dawn.
Journal of PHYSIOLOGICAL ANTHROPOLOGY 07/2007; 26(4):429-36.
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ABSTRACT: This study assesses the effects of ambient light conditions, under a thermoneutral environment, on selected immunological parameters of 7 healthy young women (aged 19 to 22 yrs). Subjects entered the bioclimatic chamber at 11: 00 h, controlled at 26 degrees C and 60% relative humidity, a "neutral climate". They lead a well-regulated life in the climatic chamber (pre-condition) while exposed to dim (200 lux) or, on the next day, bright (5000 lux) light between 06 : 00 to 12 : 00 h. Just before the end of each period of light exposure, a blood sample was taken for later immunological assay of white blood cell count (WBC), phagocytosis, interferon-gamma (IFN-gamma), interleukin-4 (IL-4), CD69 T cells (CD69), CD4+CD25+ T cells (CD4+CD25+), and transforming growth factor-beta 1 (TGF-beta1). The results, when compared with the pre-condition, were as follows: 1) CD69 and IFN-gamma increased during normal conditions without thermal stress under dim light; 2) WBC increased and IL-4 decreased under bright light; 3) as shown by the highly significant decrease of TGF-beta1, the immune system was activated under bright light; 4) phagocytosis tended to increase under bright light exposure; 5) CD69 and IFN-gamma were significantly higher, and CD4+CD25+ tended to decrease under bright light; 6) phagocytosis tended to be lower and TGF-beta1 significantly higher under dim light, indicating a decline of immune system function. Taken together, this preliminary single time-point sampling study infers that some parameters are activated (CD69) while others are attenuated (phagocytosis, TGF-beta1) according to the environmental light intensity, dim vs. bright, in women adhering to a standardized routine in the absence of thermal stress. These findings are discussed in terms of inhibition of the sympathetic and excitation of the parasympathetic nervous system under the influence of life-style regularity and daytime bright light exposure.
Chronobiology International 02/2005; 22(6):1145-55. · 4.03 Impact Factor
