Poster De Conférence Année : 2025

Low-intensity artificial light at night Disrupts sleep and physiological functions in controlled laboratory conditions

Résumé

Introduction: Artificial light at night (ALAN) is becoming increasingly prevalent in modern society, disrupting natural light/dark cycles and potentially impacting human health. However, most studies on this topic lack controlled conditions, making it difficult to isolate the effects from confounding factors (noise, air pollution, population density, diet and lifestyle factors, etc.). This study aimed to investigate the effects of low-intensity ALAN on sleep and various physiological functions under controlled laboratory conditions. Materials and methods: Twenty healthy young male participants (24.2 ± 3.3 years; BMI=22.2 ± 2.2 kg/m2) underwent a 5-day and 4-night protocol in temporal isolation (in a sound-attenuated, temperature-controlled individual room, free from time cues). During their four 8-hour nightly sleep episodes at their habitual sleep times, participants were randomly assigned to one of four light conditions: 0 lux, 3 lux, 8 lux, or 20 lux (5000K broadband white light generated by a 10-channel LED system, Ledmotive Spectra Tune 10). During the day, participants were exposed to a light intensity of approximately 90 lux at the eye level (3000 K, Osram 64701). Endocrine markers (melatonin, cortisol, alpha-amylase), electrophysiological measures (EEG, ECG, pupillary light reflex), skin temperature and glycemia were measured continuously or with a sampling rate of more than one sample per hour throughout the study. Results: The results revealed that nocturnal exposure to 20 lux significantly decreased total sleep time, sleep efficiency, increased wake after sleep onset (WASO), elevated proximal body temperature and glucose levels, and increased heart rate (HR). Interestingly, overnight urinary 6-sulfatoxy-melatonin (aMT6s) and salivary cortisol levels at waketime were unaffected across all light conditions. Additionally, overnight light exposure reduced photoreceptor sensitivity to light upon awakening, but did not significantly impair cognitive performance at waketime. Conclusions: These findings demonstrate that even low levels of ALAN, as commonly encountered in real-life environments, can acutely disrupt human sleep and several physiological functions within only 1–4 days of exposure. It remains unclear whether these effects persist under chronic exposure or lead to long-term health impacts, however, the results warrant consideration, as they highlight the potential for even low-intensity ALAN, commonly encountered in real-life settings, to affect human health. Acknowledgments: NT and YH were supported by a Doctoral Fellowship from the Chinese Scholarship Council (CSC202006180019 and CSC202006180028, respectively). Funding was obtained by CG (Idex Breakthrough ALAN - ANR-16-IDEX-0005, and Rectolux from the University of Lyon).

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Dates et versions

hal-05233007 , version 1 (01-09-2025)

Identifiants

  • HAL Id : hal-05233007 , version 1

Citer

Ni Tang, Yanlong Hou, Abhishek S Prayag, Xi Wang, Tao Jiang, et al.. Low-intensity artificial light at night Disrupts sleep and physiological functions in controlled laboratory conditions. World Sleep 2025, Sep 2025, Singapore, France. ⟨hal-05233007⟩
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