was linked to higher obesity-related measures in children and adolescents, mainly among those with less than 1 hour/day of moderate-to-vigorous physical activity.
Evidence
A cross-sectional Shanghai study measured one week of indoor nighttime light in 628 participants aged 9-15 and found longer exposure to light >=1 lx associated with higher , , trunk fat, waist circumference, and obesity odds.
Caveat
The design was observational and cross-sectional, so it cannot show that nighttime light caused obesity or confirm physical activity as the modifier.
Simplified
BACKGROUND: Light at night () has been reported to be related to a variety of metabolic diseases, especially in adults. This study aimed to investigate the association between indoor LAN exposure and obesity-related parameters among children and adolescents, and to assess this association at different levels of physical activity.
METHODS: From April to December 2024, LAN exposure was collected by a portable illuminance meter over one week on 628 children and adolescents aged 9-15 years in Shanghai. Obesity-related parameters were measured by body composition analyzer and professional technicians. Moderate-to-vigorous intensity physical activity (MVPA) was assessed using Children' s Leisure Activities Study Survey-Chinese edition (CLASS-C).
RESULTS: Median indoor LAN(average light intensity from bedtime to rising time) was 2.4 lx, with 72.1% of participants experiencing an average exposure above 1 lx. Median indoor LAN1 (duration of nighttime light intensity ≥ 1 lx) was 36.1 min. Each SD (12.3 lx) increase of indoor LANwas associated with increase of 0.34 in (95% CI: 0.07, 0.61), 0.49 kg in (95% CI: 0.02, 0.96), 0.26 kg in FMT (95% CI: 0.01, 0.52). Extended exposure to LAN ≥ 1 lx by 67.0 min/day (1 SD) was related to increase of 0.42 in BMI (95% CI: 0.15, 0.69), 0.59 kg in FM (95% CI: 0.12, 1.06), 0.32 kg in FMT (95% CI: 0.07, 0.58), and 0.72 cm increase of WC (95% CI: 0.02, 1.43). LAN duration (LAN1) was significantly associated with obesity (OR = 1.27, 95% CI: 1.05, 1.53). When stratified by MVPA, associations between LAN exposure and obesity, FM, FMT, WC disappeared in participants with MVPA ≥ 1 h/day. The correlation of lighter LAN(≥ 1 lx ) with BMI, FM and FMT was positive in the level of MVPA < 1 h/day, but negative in level of MVPA ≥ 1 h/day, although no statistical significance was found (P > 0.05). avg avg avg
CONCLUSION: This population-based study provides indicates that indoor LAN is significantly related to obesity among children and adolescents. Longitudinal studies are required to confirm the potential moderating role of MVPA between LAN and obesity.
Key numbers
0.34
Increase in per SD increase in
Each SD (12.3 lx) increase in indoor exposure
0.72 cm
Increase in waist circumference per SD increase in duration
Extended exposure to ≥ 1 lx by 67.0 min/day
1.27
Odds ratio for obesity per SD increase in duration
Each SD increase in duration is significantly associated with obesity
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