Publication Date:
1986-08-08
Description:
Human circadian rhythms were once thought to be insensitive to light, with synchronization to the 24-hour day accomplished either through social contacts or the sleep-wake schedule. Yet the demonstration of an intensity-dependent neuroendocrine response to bright light has led to renewed consideration of light as a possible synchronizer of the human circadian pacemaker. In a laboratory study, the output of the circadian pacemaker of an elderly woman was monitored before and after exposure to 4 hours of bright light for seven consecutive evenings, and before and after a control study in ordinary room light while her sleep-wake schedule and social contacts remained unchanged. The exposure to bright light in the evening induced a 6-hour delay shift of her circadian pacemaker, as indicated by recordings of body temperature and cortisol secretion. The unexpected magnitude, rapidity, and stability of the shift challenge existing concepts regarding circadian phase-resetting capacity in man and suggest that exposure to bright light can indeed reset the human circadian pacemaker, which controls daily variations in physiologic, behavioral, and cognitive function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Czeisler, C A -- Allan, J S -- Strogatz, S H -- Ronda, J M -- Sanchez, R -- Rios, C D -- Freitag, W O -- Richardson, G S -- Kronauer, R E -- 1 R01-AG-04912-02/AG/NIA NIH HHS/ -- 1 R01-HD-20174-01/HD/NICHD NIH HHS/ -- AFOSR-83-0309/PHS HHS/ -- etc. -- New York, N.Y. -- Science. 1986 Aug 8;233(4764):667-71.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3726555" target="_blank"〉PubMed〈/a〉
Keywords:
Aged
;
Body Temperature
;
*Circadian Rhythm
;
Female
;
Humans
;
Hydrocortisone/blood
;
*Light
;
Sleep/*physiology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
Permalink
