Light at night disrupts biological clocks, calendars, and immune function

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Summary

Light at night disrupts biological clocks, seasonal calendars, and immune function via melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs), with implications for lighting design that minimizes nighttime light exposure. Controlling spectral composition and intensity of nighttime lighting—particularly in healthcare and residential settings—may help preserve circadian integrity and immune health.

Key Findings

Light at night disrupts biological clocks and seasonal (calendar) timekeeping through activation of melanopsin in ipRGCs, initiating action potentials that alter circadian and immune function.
The review highlights that circadian disruption from nighttime light exposure has downstream consequences for immune function, suggesting that minimizing light at night is critical for health maintenance.
ipRGCs serve as the primary conduit between environmental light and the central circadian clock, making melanopsin-based sensitivity a key target for circadian-supportive lighting strategies.