Aging does not reduce the internal clock rhythm in brain’s time-keeping center but makes it more sensitive to constant light

Under constant light conditions, 47% of aged mice exhibited completely arrhythmic SCN explants compared to 27% of adult mice.

• Aging may impair the circadian regulation of behavior, particularly under unnatural lighting conditions.
• Increased age correlates with a marginal decline in rhythmicity in the middle region of the suprachiasmatic nuclei (SCN) under constant light.
• The ability of the SCN to produce bioluminescence rhythms in vitro remains relatively unaffected by aging in standard light/dark cycles or constant darkness.
• Aging significantly impacts locomotor activity rhythms driven by the SCN despite the resilience of the core molecular clock mechanism.
• Findings suggest that age-related changes in circadian rhythms may involve pathways beyond the core clock mechanism.

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