Light-At-Night and Mood: Examining The Role Of Sex In C57Bl/6 Mice

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Summary

Exposure to ~5 lux of dim light at night did not significantly disrupt circadian rhythms or induce depressive/anxiety-like behaviors in C57Bl/6 mice, suggesting strain-specific sensitivity to nocturnal light pollution. However, neural progenitor cell proliferation in the dentate gyrus was significantly reduced in light-at-night animals, indicating a neurobiological impact even in the absence of overt behavioral changes.

Key Findings

Dim light at night (~5 lux, 12h nocturnal exposure for 3 weeks) did not produce significant circadian disruption in C57Bl/6 mice.
No significant changes were detected in most measures of depressive-like or anxiety-like behavior under dim light-at-night conditions.
Ki-67-labeled neural progenitor cells in the dentate gyrus were significantly decreased in light-at-night animals, indicating reduced hippocampal neurogenesis.
Sex-dependent effects were only detected in the Forced Swim Test; no other sex-specific behavioral differences emerged.
Results suggest species and strain differences are critical variables when evaluating the impact of nocturnal light on circadian and affective systems.

Categories

Mood & Mental Wellness: Examines whether dim light at night induces depressive- and anxiety-like behaviors in mice, with attention to sex differences.

Sleep & Circadian Health: Tests the hypothesis that dim nocturnal light disrupts circadian rhythms in C57Bl/6 mice.

The Science of Light: Investigates species/strain-specific responses to ~5 lux nocturnal light exposure and its neurobiological effects including hippocampal neurogenesis.