Seasonal changes in human sleep–wake rhythm in Antarctica and Japan

Usui, Akira; Obinata, Ichio; Ishizuka, Y.; Okado, Tamio; Fukuzawa, Hitoshi; Kanba, Shigenobu

doi:10.1046/j.1440-1819.2000.00715.x

Cited by 19 publications

(10 citation statements)

References 4 publications

(6 reference statements)

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“…A delay in sleep and other circadian outputs (melatonin and core body temperature) have been previously reported between polar winter and summer [34], [51]. Previous interventions have been designed to advance circadian phase, such as bright light exposure in the early morning.…”

Section: Discussionmentioning

confidence: 98%

Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements

Najjar

Wolf²,

Taillard

et al. 2014

PLoS ONE

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Studies in Polar Base stations, where personnel have no access to sunlight during winter, have reported circadian misalignment, free-running of the sleep-wake rhythm, and sleep problems. Here we tested light as a countermeasure to circadian misalignment in personnel of the Concordia Polar Base station during the polar winter. We hypothesized that entrainment of the circadian pacemaker to a 24-h light-dark schedule would not occur in all crew members (n = 10) exposed to 100–300 lux of standard fluorescent white (SW) light during the daytime, and that chronic non-time restricted daytime exposure to melanopsin-optimized blue-enriched white (BE) light would establish an a stable circadian phase, in participants, together with increased cognitive performance and mood levels. The lighting schedule consisted of an alternation between SW lighting (2 weeks), followed by a BE lighting (2 weeks) for a total of 9 weeks. Rest-activity cycles assessed by actigraphy showed a stable rest-activity pattern under both SW and BE light. No difference was found between light conditions on the intra-daily stability, variability and amplitude of activity, as assessed by non-parametric circadian analysis. As hypothesized, a significant delay of about 30 minutes in the onset of melatonin secretion occurred with SW, but not with BE light. BE light significantly enhanced well being and alertness compared to SW light. We propose that the superior efficacy of blue-enriched white light versus standard white light involves melanopsin-based mechanisms in the activation of the non-visual functions studied, and that their responses do not dampen with time (over 9-weeks). This work could lead to practical applications of light exposure in working environment where background light intensity is chronically low to moderate (polar base stations, power plants, space missions, etc.), and may help design lighting strategies to maintain health, productivity, and personnel safety.

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Section: Discussionmentioning

confidence: 98%

Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements

Najjar

Wolf²,

Taillard

et al. 2014

PLoS ONE

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“…The impact of the Antarctic extreme conditions of photoperiod and temperature on sleep habits has been previously reported in several long-term studies mainly focused on crewmembers of different bases [18] , [19] , [20] , [21] , [22] , [23] , [25] . With the lack of cycling environmental cues during Antarctic summers and winters, circadian rhythms tend to free-run, and this disturbance, together with the social isolation and strictness of life conditions in Antarctic bases, are key factors in the high incidence of sleep disturbances in this particular population.…”

Section: Discussionmentioning

confidence: 99%

“…During summers and winters in Antarctica, the most extreme and isolated continent on earth, the human circadian clock cannot rely on changes of photoperiod and temperature to entrain the clock day after day, and circadian rhythms might tend to free run [17] . Sleep disorders reported in Antarctic crewmembers are probably also related to this dysregulation of the external time cues [18] , [19] , [20] , [21] , [22] , [23] . However, it has been hard to establish to what extent these disorders respond to the external environment rather than to the strictness of social cues and the conditions of isolation inherent to living in an Antarctic base station [24] , [25] .…”

Section: Introductionmentioning

confidence: 99%

Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay

et al. 2016

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In humans, a person’s chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Sleep disorders have been reported in Antarctic inhabitants, that might be a response to the extreme environment or to the strictness of Antarctic life. We evaluated, for the first time in Uruguay, the chronotypes and SJL of 17 undergraduate students of the First Uruguayan Summer School on Antarctic Research, using Munich Chronotype Questionnaire (MCTQ) and sleep logs (SL) recorded during 3 phases: pre-Antarctic, Antarctic, and post-Antarctic. The midsleep point of free days corrected for sleep debt on work days (MSFsc,) was used as proxy of individuals’ chronotype, whose values (around 6 a.m.) are the latest ever reported. We found a SJL of around 2 h in average, which correlated positively with MSFsc, confirming that late chronotypes generate a higher sleep debt during weekdays. Midsleep point and sleep duration significantly decreased between pre-Antarctic and Antarctic phases, and sleep duration rebounded to significant higher values in the post-Antarctic phase. Waking time, but not sleep onset time, significantly varied among phases. This evidence suggests that sleep schedules more likely depended on the social agenda than on the environmental light–dark shifts. High motivation of students towards Antarctic activities likely induced a subjective perception of welfare non-dependent on sleep duration.

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“…A trend towards delayed sleep was evident in a small, but thorough, study at 70.37°S (Wortmann et al, 1999). Usui et al (2000) found evidence of desynchronization and phase-delayed sleep in the Antarctic midwinter in eight men of the Japanese Antarctic Research Expedition. Similarly, delayed sleep was reported in midwinter at 69°N by Bratlid and Wahlund (2003).…”

Section: Polar Studiesmentioning

confidence: 94%

Biological Rhythms During Residence in Polar Regions

Arendt¹

2012

Chronobiology International

124

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At Arctic and Antarctic latitudes, personnel are deprived of natural sunlight in winter and have continuous daylight in summer: light of sufficient intensity and suitable spectral composition is the main factor that maintains the 24-h period of human circadian rhythms. Thus, the status of the circadian system is of interest. Moreover, the relatively controlled artificial light conditions in winter are conducive to experimentation with different types of light treatment. The hormone melatonin and/or its metabolite 6-sulfatoxymelatonin (aMT6s) provide probably the best index of circadian (and seasonal) timing. A frequent observation has been a delay of the circadian system in winter. A skeleton photoperiod (2 × 1-h, bright white light, morning and evening) can restore summer timing. A single 1-h pulse of light in the morning may be sufficient. A few people desynchronize from the 24-h day (free-run) and show their intrinsic circadian period, usually >24 h. With regard to general health in polar regions, intermittent reports describe abnormalities in various physiological processes from the point of view of daily and seasonal rhythms, but positive health outcomes are also published. True winter depression (SAD) appears to be rare, although subsyndromal SAD is reported. Probably of most concern are the numerous reports of sleep problems. These have prompted investigations of the underlying mechanisms and treatment interventions. A delay of the circadian system with “normal” working hours implies sleep is attempted at a suboptimal phase. Decrements in sleep efficiency, latency, duration, and quality are also seen in winter. Increasing the intensity of ambient light exposure throughout the day advanced circadian phase and was associated with benefits for sleep: blue-enriched light was slightly more effective than standard white light. Effects on performance remain to be fully investigated. At 75°S, base personnel adapt the circadian system to night work within a week, in contrast to temperate zones where complete adaptation rarely occurs. A similar situation occurs on high-latitude North Sea oil installations, especially when working 18:00–06:00 h. Lack of conflicting light exposure (and “social obligations”) is the probable explanation. Many have problems returning to day work, showing circadian desynchrony. Timed light treatment again has helped to restore normal phase/sleep in a small number of people. Postprandial response to meals is compromised during periods of desynchrony with evidence of insulin resistance and elevated triglycerides, risk factors for heart disease. Only small numbers of subjects have been studied intensively in polar regions; however, these observations suggest that suboptimal light conditions are deleterious to health. They apply equally to people living in temperate zones with insufficient light exposure.

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Seasonal changes in human sleep–wake rhythm in Antarctica and Japan

Cited by 19 publications

References 4 publications

Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements

Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements

Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay

Biological Rhythms During Residence in Polar Regions

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