Research
Hormonal
Reduced sensitivity to light due to lens yellowing and reduced SCN neuronal coupling contributes to the desynchronization of peripheral clocks and weakened circadian output in older adults.
Your eyes let in less blue light as you age, weakening your body's time signal. Maximizing morning outdoor light exposure can help compensate for this reduced sensitivity and strengthen your circadian rhythm.
GoodSupportsHIGH confidence
Progressive yellowing and thickening of the lens may reduce sensitivity to light, the strongest zeitgeber. Reduction of AVP and VIP expression and fewer GABAergic synapses may decrease signaling within the SCN, leading to a decrease in the overall amplitude of its firing rhythm.
Why this rating
Supported by multiple studies on lens optics, SCN morphology, and neuronal coupling in rodents and humans.
Source
The aging clock: circadian rhythms and later life
Suzanne Hood et al. · Journal of Clinical Investigation · 2017
DOI 10.1172/jci90328
narrative_reviewCited 603×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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- Aging is associated with a progressive dampening of circadian rhythm amplitude and a phase advance in chronotype, leading to sleep fragmentation and increased susceptibility to metabolic and neurodegenerative diseases.Good
- Timed food restriction or scheduled meal timing can serve as a potent non-photic zeitgeber to resynchronize peripheral clocks and improve activity rhythms in aged individuals, potentially mitigating age-associated pathologies.Moderate
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