Chronic exposure to dim light at night disrupts cell-mediated immune response and decreases longevity in aged female mice

Oct 21, 2022Chronobiology international

Long-term dim light at night weakens immune response and shortens lifespan in older female mice

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Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Chronic exposure to dim artificial light at night (dLAN) for 24 weeks affects lifespan in aged female mice.

Aged female mice exposed to dLAN showed dysregulated immune response and increased inflammation.
Lifespan decreased in female mice exposed to dLAN compared to those in dark conditions.
Nighttime lighting did not affect immune response or lifespan in male mice.
Male mice exposed to dLAN exhibited changes in body mass and increased adrenal mass after immune challenge.
These findings suggest that aged females may be more vulnerable to the negative effects of disrupted circadian rhythms.

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Circadian rhythms are endogenous biological cycles that regulate physiology and behavior for optimal adaptive function and survival; they are synchronized to precisely 24 hours by daily light exposure. Disruption of the daily light-dark (LD) cycle by exposure to artificial light at night (ALAN) dysregulates core clock genes and biological function. Exposure to ALAN has been associated with increased health risks in humans, and elderly individuals are at elevated risk for poor outcome from disease and often experience elevated exposure to ALAN due to increased care requirements. The role of disrupted circadian rhythms in healthy, aged animals remains unspecified; thus, we hypothesized that disrupted circadian rhythms via chronic exposure to dim ALAN (dLAN) impair immune response and survival in aged mice. Twenty-month-old C57BL/6 male and female mice were exposed to 24 weeks of LD conditions or dLAN (5 lux); then, cell-mediated immune response was assessed using a delayed-type hypersensitivity test. Aged female mice exposed to dLAN displayed dysregulated hypersensitivity and inflammation as a measure of cell-mediated immune response and decreased lifespan compared to females housed in dark nights. Nighttime lighting did not affect cell-mediated immune response or lifespan in males but dysregulated body mass and increased adrenal mass after immune challenge after chronic exposure to dLAN. Together, these data indicate that chronic exposure to dLAN affects lifespan in aged females and suggest that females are more susceptible to the detrimental consequences of disrupted circadian rhythms.

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Chronic exposure to dim light at night disrupts cell-mediated immune response and decreases longevity in aged female mice

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