Light Exposure Rhythms and Sleep Organization in Adolescents: Temporal Differences Between Weekdays and Weekends in an Actigraphic Study

Apr 24, 2026Clocks & sleep

Daily Light Exposure Patterns and Sleep Timing in Teens: Differences Between Weekdays and Weekends

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Abstract

Eighteen adolescents monitored over seven days showed longer total sleep time and time in bed on weekdays compared to weekends (< 0.05).

Sleep latency and wake after sleep onset (WASO) did not differ between weekdays and weekends.
Circadian rhythm indices indicated preserved rhythmic organization throughout the week.
Light exposure exhibited a strong daily pattern, with higher levels of light intensity on weekends (< 0.001), particularly in the morning and early afternoon.
Significant interactions between time of day and day type were observed across all light spectral bands (< 0.001), indicating systematic changes in daily light exposure profiles.
Differences in light exposure patterns on weekdays and weekends may influence the overall sleep-wake cycles of adolescents.

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Light exposure is a primary zeitgeber for the human circadian system and plays a key role in shaping sleep-wake patterns during adolescence, a period marked by biological sensitivity and social constraints. How the temporal organization and spectral composition of daily light exposure differ between weekdays and weekends remains poorly understood. Eighteen adolescents (15-17 years) were monitored for seven days using wrist actigraphy with integrated light sensors. Sleep parameters, nonparametric circadian rhythm indices, and time-resolved profiles of ambient and spectral (blue, green, and red) light exposure were analyzed. Repeated-measures ANOVA tested the effects of time of day and day type. Total sleep time and time in bed were longer on weekdays than on weekends (< 0.05), while sleep latency and WASO did not differ. Circadian indices indicated preserved rhythmic organization. Light exposure showed a robust diurnal profile, with higher spectral irradiance on weekends (< 0.001), especially in the morning and early afternoon. Significant time × day-type interactions were observed across all spectral bands (< 0.001), indicating systematic reshaping of daily light profiles. Adolescents exhibit weekday-weekend differences in the temporal and spectral organization of light exposure, affecting the amplitude and shape of overall daily profiles. p p p

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Circadian BiologyIssue #34

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Light Exposure Rhythms and Sleep Organization in Adolescents: Temporal Differences Between Weekdays and Weekends in an Actigraphic Study

Abstract

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