Summary
Prior exposure to short winter-like photoperiods dramatically increases the circadian system's sensitivity to light, with a 40-fold increase in photic sensitivity for phase advances and approximately two-fold greater maximal phase shifts compared to longer photoperiods. These findings have practical implications for lighting design, suggesting that the effective dose of light needed to shift circadian rhythms may vary substantially depending on a person's recent light history and season.
Key Findings
- 40-fold increase in photic sensitivity for phase advancing of activity rhythms in Syrian hamsters previously entrained to shorter (winter-like) photoperiods compared to longer days
- Approximately 2-fold greater maximal phase shift following entrainment to short winter-like photoperiod compared to longer summer-like photoperiods (Goldman and Elliott, 1988; Evans et al., 2004)
- Photoperiod history also modulates circadian phase delays, light sampling behavior, light-induced melatonin suppression, and photic induction of proteins in the SCN
Categories
Sleep & Circadian Health: Investigates how photoperiod history modulates circadian entrainment, phase shifts, and melatonin suppression via the non-image-forming visual system.
The Science of Light: Characterizes photic sensitivity of the circadian system as a function of prior light exposure, including SCN protein induction and melanopsin-related pathways.
Author(s)
GL Glickman
Publication Year
2013
Related Publications
Sleep & Circadian Health
- Phototransduction by retinal ganglion cells that set the circadian clock
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- The twoāprocess model of sleep regulation: a reappraisal
- Melanopsin is required for non-image-forming photic responses in blind mice
- Strange vision: ganglion cells as circadian photoreceptors
The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice