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Author (up) Christie, S.; Vincent, A.D.; Li, H.; Frisby, C.L.; Kentish, S.J.; O'Rielly, R.; Wittert, G.A.; Page, A.J. url  doi
openurl 
  Title A rotating light cycle promotes weight gain and hepatic lipid storage in mice Type Journal Article
  Year 2018 Publication American Journal of Physiology. Gastrointestinal and Liver Physiology Abbreviated Journal Am J Physiol Gastrointest Liver Physiol  
  Volume in press Issue Pages  
  Keywords Animals  
  Abstract Processes involved in regulation of energy balance and intermediary metabolism are aligned to the light-dark cycle. Shift-work and high fat diet (HFD)-induced obesity disrupt circadian rhythmicity and are associated with increased risk of non-alcoholic fatty liver disease (NAFLD). This study aimed to determine the effect of simulating shift work on hepatic lipid accumulation in lean and HFD-mice. C57BL/6 mice fed a standard laboratory diet (SLD) or HFD for 4wks were further allocated to a normal light (NL)-cycle (lights on:0600-1800hr) or rotating light (RL)-cycle (3-days NL and 4-days reversed (lights on:1800-0600hr) repeated) for 8wks. Tissue was collected every 3hrs beginning at 0600hr. HFD-mice gained more weight than SLD-mice, and RL-mice gained more weight than NL-mice. SLD-NL and HFD-NL mice, but not RL-mice, were more active, had higher respiratory quotients and consumed/expended more energy during the dark phase compared to the light phase. Blood glucose and plasma cholesterol and triglyceride concentrations were elevated in HFD and SLD-RL compared to SLD-NL mice. Hepatic glycogen was elevated in HFD compared to SLD-mice. Hepatic triglycerides were elevated in SLD-RL and HFD-mice compared to SLD-NL. Circadian rhythmicity of hepatic acetyl-CoA carboxylase (ACACA) mRNA was phase shifted in SLD-RL and HFD-NL and lost in HFD-RL mice. Hepatic ACACA protein was reduced in SLD-RL and HFD-mice compared to SLD-NL mice. Hepatic adipose triglyceride lipase was elevated in HFD-NL compared to SLD-NL but lower in RL-mice compared to NL-mice irrespective of diet. -Conclusion: A RL-cycle model of shift-work promotes weight gain and hepatic lipid storage even in lean conditions.  
  Address Adelaide Medical School, University of Adelaide, Australia  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0193-1857 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30188750 Approved no  
  Call Number GFZ @ kyba @ Serial 2123  
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Author (up) Gatford, K.L.; Kennaway, D.J.; Liu, H.; Kleemann, D.O.; Kuchel, T.R.; Varcoe, T.J. url  doi
openurl 
  Title Simulated shift work disrupts maternal circadian rhythms and metabolism, and increases gestation length in sheep Type Journal Article
  Year 2019 Publication The Journal of Physiology Abbreviated Journal J Physiol  
  Volume 597 Issue 7 Pages 1889-1904  
  Keywords Animals; *Circadian Rhythm; Female; Fetal Development; Pregnancy; *Pregnancy, Animal/physiology; Pregnancy, Multiple; Sheep/*physiology; *Shift Work Schedule; Sleep/*physiology; *circadian rhythms; *fetus; *maternal; *pregnancy; *sheep; *shift work  
  Abstract KEY POINTS: Shift work impairs metabolic health, although its effects during pregnancy are not well understood We evaluated the effects of a simulated shift work protocol for one-third, two-thirds or all of pregnancy on maternal and pregnancy outcomes in sheep. Simulated shift work changed the timing of activity, disrupted hormonal and cellular rhythms, and impaired maternal glucose tolerance during early pregnancy. Gestation length was increased in twin pregnancies, whereas singleton lambs were lighter at a given gestational age if mothers were subjected to shift work conditions in the first one-third of pregnancy. Exposure to rotating night and day shifts, even if only in early pregnancy, may adversely affect maternal metabolic and pregnancy outcomes. ABSTRACT: Shift workers are at increased risk of developing type 2 diabetes and obesity; however, the impact during pregnancy on maternal metabolism is unknown. Using a large animal model, we assessed the impact of simulated shift work (SSW) exposure during pregnancy on maternal circadian rhythms, glucose tolerance and pregnancy outcomes. Following mating, ewes were randomly allocated to a control photoperiod (CON 12 h light, 12 h dark) or to SSW, where the timing of light exposure and food presentation was reversed twice each week for one-third, two-thirds or all of pregnancy. Maternal behaviour followed SSW cycles with increased activity during light exposure and feeding. Melatonin rhythms resynchronized within 2 days of the photoperiod shift, whereas peripheral circadian rhythms were arrhythmic. SSW impaired glucose tolerance (+29%, P = 0.019) and increased glucose-stimulated insulin secretion (+32%, P = 0.018) in ewes with a singleton fetus in early but not late gestation. SSW exposure did not alter rates of miscarriage or stillbirth, although it extended gestation length in twin pregnancies (+2.4 days, P = 0.032). Relative to gestational age, birth weight was lower in singleton progeny of SSW than CON ewes (-476 g, P = 0.016). These results have implications for the large number of women currently engaged in shift work, and further studies are required to determine progeny health impacts.  
  Address Robinson Research Institute, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3751 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30671970; PMCID:PMC6441904 Approved no  
  Call Number GFZ @ kyba @ Serial 3136  
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Author (up) Gatford, K.L.; Kennaway, D.J.; Liu, H.; Schultz, C.G.; Wooldridge, A.L.; Kuchel, T.R.; Varcoe, T.J. url  doi
openurl 
  Title Simulated shift work during pregnancy does not impair progeny metabolic outcomes in sheep Type Journal Article
  Year 2020 Publication The Journal of Physiology Abbreviated Journal J Physiol  
  Volume in press Issue Pages in press  
  Keywords Animals; developmental programming; maternal; metabolism; progeny; sheep; shift work  
  Abstract KEY POINTS: Maternal shift work increases the risk of pregnancy complications, although its effects on progeny health after birth were not clear. We evaluated the impact of a simulated shift work protocol for one third, two thirds, or all of pregnancy on metabolic health of sheep progeny. Simulated shift work had no effect on growth, body size, body composition or glucose tolerance in pre-pubertal or young adult progeny. Glucose stimulated insulin secretion was reduced in adult female progeny and insulin sensitivity was increased in adult female singleton progeny. The results of this study does not support the hypothesis that maternal shift work exposure impairs metabolic health of progeny in altricial species ABSTRACT: Disrupted maternal circadian rhythms, such as those experienced during shift work, are associated with impaired progeny metabolism in rodents. The effects of disrupted maternal circadian rhythms on progeny metabolism have not been assessed in altricial, non-litter bearing species. We therefore assessed postnatal growth from birth to adulthood, and body composition, glucose tolerance, insulin secretion and insulin sensitivity in pre-pubertal and young adult progeny of sheep exposed to control conditions (CON: 10 males, 10 females) or to a simulated shift work (SSW) protocol for the first 1/3 (SSW0-7: 11 males, 9 females), the first 2/3 (SSW0-14: 8 males, 11 females), or all (SSW0-21: 8 males, 13 females) of pregnancy. Progeny growth did not differ between maternal treatments. In pre-pubertal progeny (12-14 weeks of age), adiposity, glucose tolerance and insulin secretion during an intravenous glucose tolerance test and insulin sensitivity did not differ between maternal treatments. Similarly, in young adult progeny (12-14 months of age), food intake, adiposity and glucose tolerance did not differ between maternal treatments. At this age, however, insulin secretion in response to a glucose bolus was 30% lower in female progeny in the combined SSW groups compared to control females (P = 0.031), and insulin sensitivity of SSW0-21 singleton females was 236% that of CON singleton female progeny (P = 0.025). At least in this model, maternal SSW does not impair progeny metabolic health, with some evidence of greater insulin action in female young adult progeny. This article is protected by copyright. All rights reserved.  
  Address Basil Hetzel Research Institute for Translational Health Research, Adelaide, South Australia, 5011, Australia  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3751 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:32918750 Approved no  
  Call Number GFZ @ kyba @ Serial 3135  
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Author (up) Higuchi, S.; Fukuda, T.; Kozaki, T.; Takahashi, M.; Miura, N. url  doi
openurl 
  Title Effectiveness of a Red-visor Cap for Preventing Light-induced Melatonin Suppression during Simulated Night Work Type Journal Article
  Year 2011 Publication Journal of PHYSIOLOGICAL ANTHROPOLOGY Abbreviated Journal J Physiol Anthropol  
  Volume 30 Issue 6 Pages 251-258  
  Keywords Human Health  
  Abstract Bright light at night improves the alertness of night workers. Melatonin suppression induced by light at night is, however, reported to be a possible risk factor for breast cancer. Short-wavelength light has a strong impact on melatonin suppression. A red-visor cap can cut the short-wavelength light from the upper visual field selectively with no adverse effects on visibility. The purpose of this study was to investigate the effects of a red-visor cap on light-induced melatonin suppression, performance, and sleepiness at night. Eleven healthy young male adults (mean age: 21.2±0.9 yr) volunteered to participate in this study. On the first day, the subjects spent time in dim light (<15 lx) from 20:00 to 03:00 to measure baseline data of nocturnal salivary melatonin concentration. On the second day, the subjects were exposed to light for four hours from 23:00 to 03:00 with a nonvisor cap (500 lx), red-visor cap (approx. 160 lx) and blue-visor cap (approx. 160 lx). Subjective sleepiness and performance of a psychomotor vigilance task (PVT) were also measured on the second day. Compared to salivary melatonin concentration under dim light, the decrease in melatonin concentration was significant in a nonvisor cap condition but was not significant in a red-visor cap condition. The percentages of melatonin suppression in the nonvisor cap and red-visor cap conditions at 4 hours after exposure to light were 52.6±22.4% and 7.7±3.3%, respectively. The red-visor cap had no adverse effect on performance of the PVT, brightness and visual comfort, though it tended to increase subjective sleepiness. These results suggest that a red-visor cap is effective in preventing melatonin suppression with no adverse effects on vigilance performance, brightness and visibility.  
  Address  
  Corporate Author Thesis  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1880-6791 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number LoNNe @ christopher.kyba @ Serial 521  
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Author (up) Kozaki, T.; Hidaka, Y.; Takakura, J.-Y.; Kusano, Y. url  doi
openurl 
  Title Suppression of salivary melatonin secretion under 100-Hz flickering and non-flickering blue light Type Journal Article
  Year 2018 Publication Journal of Physiological Anthropology Abbreviated Journal J Physiol Anthropol  
  Volume 37 Issue 1 Pages 23  
  Keywords Human Health  
  Abstract BACKGROUND: Bright light at night is known to suppress melatonin secretion. Novel photoreceptors named intrinsically photosensitive retinal ganglion cells (ipRGCs) are mainly responsible for projecting dark/bright information to the suprachiasmatic nucleus and thus regulating the circadian system. However, it has been shown that the amplitude of the electroretinogram of ipRGCs is considerably lower under flickering light at 100 Hz than at 1-5 Hz, suggesting that flickering light may also affect the circadian system. Therefore, in this study, we evaluated light-induced melatonin suppression under flickering and non-flickering light. METHODS: Twelve male participants between the ages of 20 and 23 years (mean +/- S.D. = 21.6 +/- 1.5 years) were exposed to three light conditions (dim, 100-Hz flickering, and non-flickering blue light) from 1:00 A.M. to 2:30 A.M., and saliva samples were obtained just before 1:00 A.M. and at 1:15, 1:30, 2:00, and 2:30 A.M. RESULTS: A repeated measures t test with Bonferroni correction showed that at 1:15 A.M., melatonin concentrations were significantly lower following exposure to non-flickering light compared with dim light, whereas there was no significant difference between the dim and 100-Hz flickering light conditions. By contrast, after 1:30 A.M., the mean melatonin concentrations were significantly lower under both 100-Hz flickering and non-flickering light than under dim light. CONCLUSION: Although melatonin suppression rate tended to be lower under 100-Hz flickering light than under non-flickering light at the initial 15 min of the light exposure, the present study suggests that 100-Hz flickering light may have the same impact on melatonin secretion as non-flickering light.  
  Address Department of Health and Nutrition Sciences, Nishikyushu University, Kanzaki, Japan  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1880-6791 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30340620 Approved no  
  Call Number GFZ @ kyba @ Serial 2039  
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Author (up) Kozaki, T.; Kubokawa, A.; Taketomi, R.; Hatae, K. url  doi
openurl 
  Title Effects of day-time exposure to different light intensities on light-induced melatonin suppression at night Type Journal Article
  Year 2015 Publication Journal of Physiological Anthropology Abbreviated Journal J Physiol Anthropol  
  Volume 34 Issue 1 Pages 27  
  Keywords Human Health  
  Abstract BACKGROUND: Bright nocturnal light has been known to suppress melatonin secretion. However, bright light exposure during the day-time might reduce light-induced melatonin suppression (LIMS) at night. The effective proportion of day-time light to night-time light is unclear; however, only a few studies on accurately controlling both day- and night-time conditions have been conducted. This study aims to evaluate the effect of different day-time light intensities on LIMS. METHODS: Twelve male subjects between the ages of 19 and 23 years (mean +/- S.D., 20.8 +/- 1.1) gave informed consent to participate in this study. They were exposed to various light conditions (<10, 100, 300, 900 and 2700 lx) between the hours of 09:00 and 12:00 (day-time light conditions). They were then exposed to bright light (300 lx) again between 01:00 and 02:30 (night-time light exposure). They provided saliva samples before (00:55) and after night-time light exposure (02:30). RESULTS: A one-tailed paired t test yielded significant decrements of melatonin concentration after night-time light exposure under day-time dim, 100- and 300-lx light conditions. No significant differences exist in melatonin concentration between pre- and post-night-time light exposure under day-time 900- and 2700-lx light conditions. CONCLUSIONS: Present findings suggest the amount of light exposure needed to prevent LIMS caused by ordinary nocturnal light in individuals who have a general life rhythm (sleep/wake schedule). These findings may be useful in implementing artificial light environments for humans in, for example, hospitals and underground shopping malls.  
  Address Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Fukuoka city, Minami-ku, Japan. hatae.keisuke.725@s.kyushu-u.ac.jp  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1880-6791 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:26141542; PMCID:PMC4491270 Approved no  
  Call Number LoNNe @ christopher.kyba @ Serial 1210  
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Author (up) Lee, S.; Kakitsuba, N.; Katsuura, T. url  doi
openurl 
  Title Do green-blocking glasses enhance the nonvisual effects of white polychromatic light? Type Journal Article
  Year 2018 Publication Journal of Physiological Anthropology Abbreviated Journal J Physiol Anthropol  
  Volume 37 Issue 1 Pages 29  
  Keywords Human Health; Vision  
  Abstract BACKGROUND: It is well known that light containing the blue component stimulates the intrinsically photosensitive retinal ganglion cells (ipRGCs) and plays a role in melatonin suppression and pupillary constriction. In our previous studies, we verified that simultaneous exposure to blue and green light resulted in less pupillary constriction than blue light exposure. Hence, we hypothesized that the nonvisual effects of polychromatic white light might be increased by blocking the green component. Therefore, we conducted an experiment using optical filters that blocked blue or green component and examined the nonvisual effects of these lights on pupillary constriction and electroencephalogram power spectra. METHODS: Ten healthy young males participated in this study. The participant sat on a chair with his eyes facing an integrating sphere. After 10 min of light adaptation, the participant's left eye was exposed to white pulsed light (1000 lx; pulse width 2.5 ms) every 10 s with a blue-blocking glasses, a green-blocking glasses, or control glasses (no lens), and pupillary constriction was measured. Then, after rest for 10 min, the participant was exposed a continuous white light of 1000 lx with a blue- or green-blocking glasses or control glasses and electroencephalogram was measured. RESULTS: Pupillary constriction with the blue-blocking glasses was significantly less than that observed with the green-blocking glasses. Furthermore, pupillary constriction under the green-blocking glasses was significantly greater than that observed with the control glasses. CONCLUSIONS: A reduction in the green component of light facilitated pupillary constriction. Thus, the effects of polychromatic white light containing blue and green components on ipRGCs are apparently increased by removing the green component.  
  Address Graduate School of Engineering, Chiba University, Chiba, Japan  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1880-6791 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:30563575; PMCID:PMC6299521 Approved no  
  Call Number GFZ @ kyba @ Serial 2153  
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Author (up) Rahman, S.A.; St Hilaire, M.A.; Gronfier, C.; Chang, A.-M.; Santhi, N.; Czeisler, C.A.; Klerman, E.B.; Lockley, S.W. url  doi
openurl 
  Title Functional decoupling of melatonin suppression and circadian phase resetting in humans Type Journal Article
  Year 2018 Publication The Journal of Physiology Abbreviated Journal J Physiol  
  Volume 596 Issue 11 Pages 2147-2157  
  Keywords Human Health  
  Abstract KEY POINTS: There is assumed to be a monotonic association between melatonin suppression and circadian phase resetting induced by light exposure. We tested the association between melatonin suppression and phase resetting in humans. Sixteen young healthy participants received nocturnal bright light ( approximately 9500 lux) exposure of continuous or intermittent patterns, and different durations ranging from 12 min to 6.5 h. Intermittent exposure patterns showed significant phase shifts with disproportionately less melatonin suppression. Each and every bright light stimulus in an intermittent exposure pattern induced a similar degree of melatonin suppression, but did not appear to cause an equal magnitude of phase shift. These results suggest that phase shifts and melatonin suppression are functionally independent such that one cannot be used as a proxy measure of the other. ABSTRACT: Continuous experimental light exposures show that, in general, the conditions that produce greater melatonin suppression also produce greater phase shift, leading to the assumption that one can be used as a proxy for the other. We tested this association in 16 healthy individuals who participated in a 9-day inpatient protocol by assessing melatonin suppression and phase resetting in response to a nocturnal light exposure (LE) of different patterns: (i) dim-light control (<3 lux; n = 6) or (ii) two 12-min intermittent bright light pulses (IBL) separated by 36 min of darkness ( approximately 9500 lux; n = 10). We compared these results with historical data from additional LE patterns: (i) dim-light control (<3 lux; n = 11); (ii) single continuous bright light exposure of 12 min (n = 9), 1.0 h (n = 10) or 6.5 h (n = 6); or (iii) an IBL light pattern consisting of six 15-min pulses with 1.0 h dim-light recovery intervals between them during a total of 6.5 h (n = 7). All light exposure groups had significantly greater phase-delay shifts than the dim-light control condition (P < 0.0001). While a monotonic association between melatonin suppression and circadian phase shift was observed, intermittent exposure patterns showed significant phase shifts with disproportionately less melatonin suppression. Each and every IBL stimulus induced a similar degree of melatonin suppression, but did not appear to cause an equal magnitude of phase shift. These results suggest unique specificities in how light-induced phase shifts and melatonin suppression are mediated such that one cannot be used as a proxy measure of the other.  
  Address Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3751 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:29707782 Approved no  
  Call Number GFZ @ kyba @ Serial 1887  
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Author (up) Revell, V.L.; Molina, T.A.; Eastman, C.I. url  doi
openurl 
  Title Human phase response curve to intermittent blue light using a commercially available device Type Journal Article
  Year 2012 Publication The Journal of Physiology Abbreviated Journal J Physiol  
  Volume 590 Issue Pt 19 Pages 4859-4868  
  Keywords Adolescent; Adult; Circadian Clocks/physiology/*radiation effects; Female; Humans; *Light; Male; Melatonin/analysis/physiology; Saliva/chemistry; Young Adult; blue light  
  Abstract Light shifts the timing of the circadian clock according to a phase response curve (PRC). To date, all human light PRCs have been to long durations of bright white light. However, melanopsin, the primary photopigment for the circadian system, is most sensitive to short wavelength blue light. Therefore, to optimise light treatment it is important to generate a blue light PRC.We used a small, commercially available blue LED light box, screen size 11.2 x 6.6 cm at approximately 50 cm, approximately 200 muW cm(-2), approximately 185 lux. Subjects participated in two 5 day laboratory sessions 1 week apart. Each session consisted of circadian phase assessments to obtain melatonin profiles before and after 3 days of free-running through an ultradian light-dark cycle (2.5 h wake in dim light, 1.5 h sleep in the dark), forced desynchrony protocol. During one session subjects received intermittent blue light (three 30 min pulses over 2 h) once a day for the 3 days of free-running, and in the other session (control) they remained in dim room light, counterbalanced. The time of blue light was varied among subjects to cover the entire 24 h day. For each individual, the phase shift to blue light was corrected for the free-run determined during the control session. The blue light PRC had a broad advance region starting in the morning and extending through the afternoon. The delay region started a few hours before bedtime and extended through the night. This is the first PRC to be constructed to blue light and to a stimulus that could be used in the real world.  
  Address University of Surrey, Guildford, Surrey GU2 7XH, UK  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3751 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:22753544; PMCID:PMC3487041 Approved no  
  Call Number IDA @ john @ Serial 345  
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Author (up) Ruger, M.; Gordijn, M.C.M.; Beersma, D.G.M.; de Vries, B.; Daan, S. url  doi
openurl 
  Title Time-of-day-dependent effects of bright light exposure on human psychophysiology: comparison of daytime and nighttime exposure Type Journal Article
  Year 2006 Publication American Journal of Physiology. Regulatory, Integrative and Comparative Physiology Abbreviated Journal Am J Physiol Regul Integr Comp Physiol  
  Volume 290 Issue 5 Pages R1413-20  
  Keywords Human Health; Adult; Body Temperature/*physiology; Circadian Rhythm/*physiology; Fatigue/*physiopathology; Heart Rate/*physiology; Humans; Hydrocortisone/*blood; *Light; Sleep Stages/*physiology  
  Abstract Bright light can influence human psychophysiology instantaneously by inducing endocrine (suppression of melatonin, increasing cortisol levels), other physiological changes (enhancement of core body temperature), and psychological changes (reduction of sleepiness, increase of alertness). Its broad range of action is reflected in the wide field of applications, ranging from optimizing a work environment to treating depressed patients. For optimally applying bright light and understanding its mechanism, it is crucial to know whether its effects depend on the time of day. In this paper, we report the effects of bright light given at two different times of day on psychological and physiological parameters. Twenty-four subjects participated in two experiments (n = 12 each). All subjects were nonsmoking, healthy young males (18-30 yr). In both experiments, subjects were exposed to either bright light (5,000 lux) or dim light <10 lux (control condition) either between 12:00 P.M. and 4:00 P.M. (experiment A) or between midnight and 4:00 A.M. (experiment B). Hourly measurements included salivary cortisol concentrations, electrocardiogram, sleepiness (Karolinska Sleepiness Scale), fatigue, and energy ratings (Visual Analog Scale). Core body temperature was measured continuously throughout the experiments. Bright light had a time-dependent effect on heart rate and core body temperature; i.e., bright light exposure at night, but not in daytime, increased heart rate and enhanced core body temperature. It had no significant effect at all on cortisol. The effect of bright light on the psychological variables was time independent, since nighttime and daytime bright light reduced sleepiness and fatigue significantly and similarly.  
  Address Department of Chronobiology, University of Groningen, The Netherlands. Melanie.Rueger@med.nyu.edu  
  Corporate Author Thesis  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0363-6119 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16373441 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 801  
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