Segmented sleep in a nonelectric, small‐scale agricultural society in Madagascar

Samson, David R.; Manus, Melissa B.; Krystal, Andrew D.; Fakir, Efe; Yu, James J.; Nunn, Charles L.

doi:10.1002/ajhb.22979

Cited by 48 publications

(76 citation statements)

References 51 publications

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“…Furthermore, there was no effect on wake time or total sleep duration, despite impacts on circadian timing. Similarly, in a rural community in Madagascar, the use of electric field lanterns for one week had no effect on participants' sleep (Samson et al, 2017b). In another study, researchers took eight participants camping without electric lights (Wright et al, 2013).…”

Section: Human Sleep: Real-world Comparisonsmentioning

confidence: 99%

“…Accordingly, a laboratory study found that people adopted biphasic sleep when exposed to 14 hr of darkness each night (Wehr, 1992). There is also evidence of biphasic sleep in some contemporary communities without electricity (Samson et al, 2017b), but not others (Beale et al, 2017;de la Iglesia et al, 2015;Peixoto, da Silva, Carskadon, & Louzada, 2009;Samson, Crittenden, Mabulla, Mabulla, & Nunn, 2017a;Yetish et al, 2015). Despite some dispute about the likely origins of biphasic sleep in humans (Ekirch, 2016;Yetish et al, 2015), sleep in western societies has clearly changed in recent history (Ekirch, 2015).…”

Section: Human Sleep: Real-world Comparisonsmentioning

confidence: 99%

“…While a connection between ALAN and sleep has been deemed “intuitive” (Chepesiuk, ), research outcomes are often conflicting and our understanding is far from complete. For example, some studies indicate that ALAN reduces sleep duration in humans (Cho et al., ; de la Iglesia et al., ; Ohayon & Milesi, ), whereas others show no such effect (Beale et al., ; Chang, Aeschbach, Duffy, & Czeisler, ; Cho, Joo, Koo, & Hong, ; Samson et al., ; Wams et al., ). Even without affecting the duration of sleep, exposure to ALAN can disrupt the timing and composition of sleep (Beale et al., ; Chang et al., ; Chellappa et al., ; Cho et al., ; Cho et al., ; Santhi et al., ; Wams et al., ), but few studies have investigated such impacts in real‐world settings (Aulsebrook, Jones, Rattenborg, Roth, & Lesku, ; but see Wams et al., ).…”

Section: Introductionmentioning

confidence: 99%

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Impacts of artificial light at night on sleep: A review and prospectus

et al. 2018

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Natural cycles of light and darkness govern the timing of most aspects of animal behavior and physiology. Artificial light at night (ALAN)-a recent and pervasive form of pollution-can mask natural photoperiodic cues and interfere with biological rhythms. One such rhythm vulnerable to perturbation is the sleep-wake cycle. ALAN may greatly influence sleep in humans and wildlife, particularly in animals that sleep predominantly at night. There has been some recent evidence for impacts of ALAN on sleep, but critical questions remain. Some of these can be addressed by adopting approaches already entrenched in sleep research. In this paper, we review the current evidence for impacts of ALAN on sleep, highlight gaps in our understanding, and suggest opportunities for future research.

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Section: Human Sleep: Real-world Comparisonsmentioning

confidence: 99%

Section: Human Sleep: Real-world Comparisonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impacts of artificial light at night on sleep: A review and prospectus

et al. 2018

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“…One recent study found the average sleep times in three different hunter-gatherer groups range from 5.7 to 7.1 h, with an overall average of 6.5 h [27]. Another set of authors observed a nearly identical average sleep time for agriculturalists in rural Madagascar [28], while a study of a Haitian population lacking access to electricity identified the sleep duration as 7 h [29]. …”

Section: Humans Sleep Less Than Other Primatesmentioning

confidence: 99%

“…In addition, napping is less common than expected in hunter-gatherers [27], yet perhaps more common and longer in agriculturalists, potentially adding up to an hour of sleep per day [28]. Taken together, 7 h is a good upper-level estimate of typical human sleep, with many ancestral populations likely sleeping less than this when ecological or social conditions constrain options for safe sleep.…”

Section: Humans Sleep Less Than Other Primatesmentioning

confidence: 99%

Does selection for short sleep duration explain human vulnerability to Alzheimer’s disease?

Nesse

Finch

Nunn

2017

Evolution, Medicine, and Public Health

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Compared with other primates, humans sleep less and have a much higher prevalence of Alzheimer ’s disease (AD) pathology. This article reviews evidence relevant to the hypothesis that natural selection for shorter sleep time in humans has compromised the efficacy of physiological mechanisms that protect against AD during sleep. In particular, the glymphatic system drains interstitial fluid from the brain, removing extra-cellular amyloid beta (eAβ) twice as fast during sleep. In addition, melatonin—a peptide hormone that increases markedly during sleep—is an effective antioxidant that inhibits the polymerization of soluble eAβ into insoluble amyloid fibrils that are associated with AD. Sleep deprivation increases plaque formation and AD, which itself disrupts sleep, potentially creating a positive feedback cycle. These and other physiological benefits of sleep may be compromised by short sleep durations. Our hypothesis highlights possible long-term side effects of medications that reduce sleep, and may lead to potential new strategies for preventing and treating AD.

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Taking the sleep lab to the field: Biometric techniques for quantifying sleep and circadian rhythms in humans

Samson

2020

American J Hum Biol

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Objectives: Remarkably, the specifics of sleep along the human lineage have been slow to emerge, which is surprising given our distinct mental and behavioral capacity and the importance of sleep for individual health and cognitive performance. Largely due to difficultly of measuring sleep outside a controlled, clinical, and laboratory study in ambulatory individuals, human biologists have yet to undergo a thorough examination of sleep in ecologically diverse settings. Here, I outline the procedures and methods for generating sleep data in a broader ecological context with the goal of facilitating the integration of sleep and circadian analyses into human biology research. Methods: I describe the steps involved in participant recruitment, screening by way of survey instruments, and sample collection. In addition to describing field use of the traditional (but invasive) equipment such as the gold-standard application of electroencephalography (EEG), I demonstrate leading-edge noninvasive techniques for biometric devices (ie, wrist-worn actigraphy, ring worn arterial pulsometry) to generate sleep and circadian rhythms data. Results: I outline best approaches to process and analyze data-including variables such as sleep duration, 24-hour sleep time (ie, summation of night and day sleep), sleep efficiency, sleep fragmentation, and nonparametric circadian rhythms analysis to quantify circadian amplitude. Finally, I discuss comparative statistical methods that are optimized for the use of time-series data.Conclusions: This review serves as an introduction to the best practices for studying sleep-wake patterns in humans-with the goal of standardizing tools for launching new human sleep biology research initiatives across the globe.

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Segmented sleep in a nonelectric, small‐scale agricultural society in Madagascar

Abstract: Sleep in this population is segmented, similar to the "first" sleep and "second" sleep reported in the historical record. Moreover, although average sleep duration and quality were lower than documented in Western populations, circadian rhythms were more stable across days.

Cited by 48 publications

References 51 publications

Impacts of artificial light at night on sleep: A review and prospectus

Impacts of artificial light at night on sleep: A review and prospectus

Does selection for short sleep duration explain human vulnerability to Alzheimer’s disease?

Taking the sleep lab to the field: Biometric techniques for quantifying sleep and circadian rhythms in humans

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