Neural basis and biological function of masking by light in mammals: suppression of melatonin and locomotor activity.
Light influences mammalian circadian rhythms in two different ways: (1) It entrains endogenous oscillators (clocks), which regulate physiology and behavior; and (2) it affects directly and often immediately physiology and behavior (these effects are also referred to as masking). Masking effects of light on pineal melatonin, locomotor activity, and the sleep-wake cycle in mammals and man are reviewed. They seem to represent a universal response in this group. The review reveals that the mechanism of photic inhibition of melatonin is fairly well understood, whereas only little is known about the influence of light on other circadian rhythm outputs, such as locomotor activity.
Redlin
U
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University of Stuttgart, Biological Institute, Department of Animal Physiology, Germany. uwe.redlin@po.uni-stuttgart.de
D000818:Animals; D002909:Chronobiology Phenomena; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects*; D005829:Geniculate Bodies / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D008027:Light; D008550:Melatonin / Q000378:metabolism; D009043:Motor Activity / Q000502:physiology / Q000528:radiation effects; D009424:Nervous System Physiological Phenomena; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology / Q000528:radiation effects; D010870:Pineal Gland / Q000378:metabolism; D011301:Preoptic Area / Q000502:physiology / Q000528:radiation effects; D012890:Sleep / Q000502:physiology / Q000528:radiation effects; D013493:Suprachiasmatic Nucleus / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology / Q000528:radiation effects
D008550:Melatonin