A fixed morning awakening coupled with a low intensity light maintains a phase advance of the human circadian system.
The next day after an early morning awakening of human subjects coupled with a single exposure to bright light from 0600 to 0900 h, the salivary melatonin rhythm was phase advanced by about 1 h as compared with the pre-treatment profile. The phase advance was maintained for 4 days when the subjects adhered to the 0600 h awakening coupled with just low intensity light, but vanished when they slept till 0900 h. Similarly, 3 days following a twice repeated exposure to bright light from 0600 to 0900 h coupled with an early morning awakening, the salivary melatonin rhythm was phase advanced relative to the pre-treatment profile only in the subjects who adhered to the 0600 h awakening but not in those who slept till 0900 h. The findings may be used for treatment of chronobiological disorders.
Samková
L
L
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Vondrasová
D
D
Hájek
I
I
Illnerová
H
H
D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism; D012463:Saliva / Q000378:metabolism; D012890:Sleep / Q000502:physiology; D014851:Wakefulness / Q000502:physiology*
D008550:Melatonin