Research

Hormonal

Exposure to ecologically relevant dim light (5 lux) at night increases body mass and white adipose tissue in mice, independent of total caloric intake.

If you sleep with lights on, even dim ones, your body may gain weight even if you eat the same amount. Try to keep your sleeping environment as dark as possible to support healthy metabolism.

GoodSupportsHIGH confidence
mice chronically exposed to dimly illuminated, as opposed to dark, nights elevate body mass independently of changes in total daily activity or caloric intake
Laura K. Fonken et al. · Journal of Biological Rhythms · 2013

Why this rating

Controlled animal study with clear statistical significance, but results are specific to mice and may not directly translate to humans without further validation.

Source

Dim Light at Night Disrupts Molecular Circadian Rhythms and Increases Body Weight

Laura K. Fonken et al. · Journal of Biological Rhythms · 2013

DOI 10.1177/0748730413493862

mechanism_only · n=120Cited 306×
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DOI resolved against Crossref · corpus check 2026-06-10

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