Dataset Information

Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu.

ABSTRACT: It has been hypothesized that sleep in the industrialized world is in chronic deficit, due in part to evening light exposure, which delays sleep onset and truncates sleep depending on morning work or school schedules. If so, societies without electricity may sleep longer. However, recent studies of hunter-gatherers and pastoralists living traditional lifestyles without electricity report short sleep compared to industrialized population norms. To further explore the impact of lifestyles and electrification on sleep, we measured sleep by actigraphy in indigenous Melanesians on Tanna Island, Vanuatu, who live traditional subsistence horticultural lifestyles, in villages either with or without access to electricity. Sleep duration was long and efficiency low in both groups, compared to averages from actigraphy studies of industrialized populations. In villages with electricity, light exposure after sunset was increased, sleep onset was delayed, and nocturnal sleep duration was reduced. These effects were driven primarily by breastfeeding mothers living with electric lighting. Relatively long sleep on Tanna may reflect advantages of an environment in which food access is reliable, climate benign, and predators and significant social conflict absent. Despite exposure to outdoor light throughout the day, an effect of artificial evening light was nonetheless detectable on sleep timing and duration.

SUBMITTER: Smit AN

PROVIDER: S-EPMC6872597 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu.

Smit Andrea N AN Broesch Tanya T Siegel Jerome M JM Mistlberger Ralph E RE

Scientific reports 20191121 1

It has been hypothesized that sleep in the industrialized world is in chronic deficit, due in part to evening light exposure, which delays sleep onset and truncates sleep depending on morning work or school schedules. If so, societies without electricity may sleep longer. However, recent studies of hunter-gatherers and pastoralists living traditional lifestyles without electricity report short sleep compared to industrialized population norms. To further explore the impact of lifestyles and elec ...[more]

PMID: 31754265

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Project description:ImportanceSleep is a resource that has been associated with health and well-being; however, sleep insufficiency is common among adolescents.ObjectiveTo examine how delaying school start time is associated with objectively assessed sleep duration, timing, and quality in a cohort of adolescents.Design, setting, and participantsThis observational cohort study took advantage of district-initiated modifications in the starting times of 5 public high schools in the metropolitan area of Minneapolis and St Paul, Minnesota. A total of 455 students were followed up from grade 9 (May 3 to June 3, 2016) through grade 11 (March 15 to May 21, 2018). Data were analyzed from February 1 to July 24, 2019.ExposuresAll 5 participating schools started early (7:30 am or 7:45 am) at baseline (2016). At follow-up 1 (2017) and continuing through follow-up 2 (2018), 2 schools delayed their start times by 50 and 65 minutes, whereas 3 comparison schools started at 7:30 am throughout the observation period.Main outcomes and measuresWrist actigraphy was used to derive indices of sleep duration, timing, and quality. With a difference-in-difference design, linear mixed-effects models were used to estimate differences in changes in sleep time between delayed-start and comparison schools.ResultsA total of 455 students were included in the analysis (among those identifying sex, 225 girls [49.5%] and 219 boys [48.1%]; mean [SD] age at baseline, 15.2 [0.3] years). Relative to the change observed in the comparison schools, students who attended delayed-start schools had an additional mean 41 (95% CI, 25-57) objectively measured minutes of night sleep at follow-up 1 and 43 (95% CI, 25-61) at follow-up 2. Delayed start times were not associated with falling asleep later on school nights at follow-ups, and students attending these schools had a mean difference-in-differences change in weekend night sleep of -24 (95% CI, -51 to 2) minutes from baseline to follow-up 1 and -34 (95% CI, -65 to -3) minutes from baseline to follow-up 2, relative to comparison school participants. Differences in differences for school night sleep onset, weekend sleep onset latency, sleep midpoints, sleep efficiency, and the sleep fragmentation index between the 2 conditions were minimal.Conclusions and relevanceThis study found that delaying high school start times could extend adolescent school night sleep duration and lessen their need for catch-up sleep on weekends. These findings suggest that later start times could be a durable strategy for addressing population-wide adolescent sleep deficits.

Project description:ObjectiveTo evaluate whether sleep duration, timing, and variability were associated with inflammatory cytokines in a cohort of Mexico City adolescents.MethodsThe analytic sample comprised >500 adolescents who were part of an ongoing longitudinal study in Mexico City. At two time points during mid-to-late puberty (average age 14, n = 391) and late-to-post puberty (average age 16, n = 345), adolescents completed a follow-up visit that included 7-day wrist actigraphy and clinical assessment of plasma inflammatory cytokines (high-sensitivity C-reactive protein, Interleukin 1β, Interleukin 6, and Tumor Necrosis Factor ɑ). Sleep characteristics included weekday and weekend sleep duration and midpoint (median of bed and wake time), as well as sleep variability (SD of sleep duration across 7 days) and social jetlag (midpoint difference from weekdays to weekends). At each time point, multivariable linear regression models were run with log inflammatory levels as the outcome and categories of sleep characteristics as predictors, while adjusting for potential confounders (specific to each model). Analyses were run unstratified and sex-stratified.ResultsIn the mid-to-late pubertal visit, weekday sleep duration was inversely associated with natural log hs-CRP after adjustment (Q4 vs Q1: β = -0.41, 95% Confidence Interval (CI) -0.81 to -0.01) and later sleep midpoint was positively associated with log hs-CRP (Q4 vs Q1: β = 0.55, 95% CI 0.13 to 0.97). Sleep duration variability was associated with higher IL-1β among boys, while in girls social jetlag was associated with higher IL-1β and weekend sleep duration was inversely associated with IL-6. At the late-to-post pubertal visit, there were few associations except for a positive association between weekday sleep duration and hs-CRP among boys (β = 0.60, 95% CI 0.04 to 1.16) and a non-linear positive association between social jetlag and hs-CRP among girls (β = 0.80, 95% CI 0.22 to 1.37 comparing 2 to 3 h of social jetlag vs <1 h).ConclusionLater timing, shorter duration, and inconsistency of sleep were related to higher levels of inflammatory biomarkers, but associations were more evident at the mid-to-late pubertal visit than the late-to-post pubertal visit.

Dataset Information

Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu.

Publications

Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu.

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