Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies

Yetish, Gandhi; Kaplan, Hillard; Gurven, Michael; Wood, Brian M.; Pontzer, Herman; Manger, Paul R.; Wilson, Charles L.; McGregor, Ronald L.; Siegel, Jerome M.

doi:10.1016/j.cub.2015.09.046

Cited by 276 publications

(294 citation statements)

References 32 publications

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“…In addition, lighting conditions inside buildings during the day are usually of a lower intensity than natural light, especially when the daylight influx from outside is limited or prevented [3]. Consequently, many behavioral and physiological circadian variables, such as the timing of sleep-wake cycles as well as the secretion of hormones, are altered in most industrialized societies when compared to groups without electricity at home [1,4,5,6]. There is growing evidence that inadequate light during the day and light at the wrong time (i.e., during the evenings and at night) contribute to circadian misalignment, sleep problems, and many other health issues [7,8,9], also in animals [10,11,12].…”

Section: Introductionmentioning

confidence: 99%

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Münch

Nowozin²,

Regente³

et al. 2016

Neuropsychobiology

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Light during the day and darkness at night are crucial factors for proper entrainment of the human circadian system to the solar 24-h day. However, modern life and work styles have led to much more time spent indoors, often with lower daytime and higher evening/nighttime light intensity from electrical lighting than outdoors. Whether this has long-term consequences for human health is being currently investigated. We tested if bright blue-enriched morning light over several days could counteract the detrimental effects of inadequate daytime and evening lighting. In a seminaturalistic, within-between subject study design, 18 young participants were exposed to different lighting conditions on 3 evenings (blue-enriched, bright orange, or dim light), after exposure to 2 lighting conditions (mixed blue-enriched light and control light, for 3 days each) in the mornings. Subjective sleepiness, reaction times, salivary melatonin concentrations, and nighttime sleep were assessed. Exposure to the blue-enriched morning lighting showed acute wake-promoting effects and faster reaction times than with control lighting. Some of these effects persisted until the evening, and performance improved over several days. The magnitude of circadian phase shifts induced by combinations of 3 different evening and 2 morning lighting conditions were significantly smaller with the blue-enriched morning light. During the night, participants had longer total sleep times after orange light exposure than after blue light exposure in the evening. Our results indicate that bright blue-enriched morning light stabilizes circadian phase, and it could be an effective counterstrategy for poor lighting during the day and also light exposure at the wrong time, such as in the late evening.

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Section: Introductionmentioning

confidence: 99%

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Münch

Nowozin²,

Regente³

et al. 2016

Neuropsychobiology

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“…Extreme morning-person hours seemed typical and healthy a century and more ago. Before artificial light became convenient, it seemed natural for people to fall asleep within a few hours after sunset and to arise about dawn, as their farm animals do (1). Today, people at either extreme of the morningness-eveningness spectrum may complain of sleep disorders and seek medical help.…”

mentioning

confidence: 99%

“…The authors of this report suggested that the Neandertal haplotypes retained in modern humans were somehow adaptive to the patterns of seasonal sun exposures at higher latitudes. The photoperiod or daylength changes more seasonally at high latitudes, triggering seasonal responses in many species, including variations in sleep timing (1). A specific neuroendocrine and molecular theory has been proposed that explains how circadian phase delays might influence photoperiodic mechanisms, resulting in depression (14).…”

mentioning

confidence: 99%

When our body clocks run late: does it make us depressed?

Kripke¹

2016

Ann. Transl. Med.

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“…The principal findings are that their sleep duration averaged 6.9-8.5 h, with variation occurring due to changes in going to sleep, rather than their wake up time. Interestingly they slept on an average, 3.3 h after sunset, but generally woke up before sunrise[17]. Environmental temperature played a major part in regulating sleep, with falling temperatures associated with sleep.…”

Section: Sleep In Hunter-gatherersmentioning

confidence: 99%

“…A coupled relation exists between circadian and metabolic systems[26], known mechanisms postulated include hormonal and hedonic causes, alteration in cardiovascular autonomic reactivity, exposure to ambient light, and shift work[17]. The basic concordance of the internal physiological system with external environment results from a natural selection process.…”

Section: Mediators Of Adverse Consequencesmentioning

confidence: 99%

Sleep, circadian dysrhythmia, obesity and diabetes

Sridhar¹,

Sanjana²

2016

WJD

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Synchrony of biological processes with environmental cues developed over millennia to match growth, reproduction and senescence. This entails a complex interplay of genetic, metabolic, chemical, light, hormonal and hedonistic factors across life forms. Sleep is one of the most prominent rhythms where such a match is established. Over the past 100 years or so, it has been possible to disturb the synchrony between sleep-wake cycle and environmental cues. Development of electric lights, shift work and continual accessibility of the internet has disrupted this match. As a result, many non-communicable diseases such as obesity, insulin resistance, type 2 diabetes, coronary artery disease and malignancies have been attributed in part to such disruption. In this presentation a review is made of the origin and evolution of sleep studies, the pathogenic mediators for such asynchrony, clinical evidence and relevance and suggested management options to deal with the disturbances.

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Natural Sleep and Its Seasonal Variations in Three Pre-industrial Societies

Cited by 276 publications

References 32 publications

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase

When our body clocks run late: does it make us depressed?

Sleep, circadian dysrhythmia, obesity and diabetes

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