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The human circadian system adapts to prior photic history
Author(s) -
Chang AnneMarie,
Scheer Frank A. J. L.,
Czeisler Charles A.
Publication year - 2011
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2010.201194
Subject(s) - circadian rhythm , light effects on circadian rhythm , melatonin , stimulus (psychology) , phase response curve , neuroscience , biology , bacterial circadian rhythms , circadian clock , photic stimulation , dark therapy , photic zone , endocrinology , psychology , visual perception , ecology , perception , phytoplankton , nutrient , psychotherapist
Non‐technical summary The human biological clock organizes and regulates the timing of many biochemical and physiological processes, including the timing of sleep, on a daily basis. Light is the strongest time cue to the circadian clock that keeps these rhythms entrained to the 24 h day. Light exposure at night results in ‘resetting’ of the clock (phase shifting). In the current study, we examined the effects of exposing subjects to two different light levels (very dim light vs. typical room light) before exposure to a 6.5 h light exposure at night. Results showed that the very dim light level, compared to the typical room light level, prior to the light exposure at night caused a substantially greater phase shift of the melatonin rhythm and substantially greater acute melatonin suppression. Thus, prior dim light history sensitizes the human biological clock to the effect of a subsequent light exposure.