Early morning bright light phase advances the human circadian pacemaker within one day.
One day after a single exposure to bright light from 03.00 to 09.00 h the morning declines in the serum melatonin concentration were phase-advanced in all subjects relative to pre-exposure patterns by 1.2-2.6 h. The evening melatonin rise was phase-advanced in 5 out of 6 subjects by 0.6-2.2 h. The data suggest that an underlying human circadian pacemaker controlling the melatonin rhythm may be phase-advanced within one day; however, the evening melatonin rise and the morning decline do not necessarily phase-shift by the same amount.
Buresová
M
M
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
Dvoráková
M
M
Zvolský
P
P
Illnerová
H
H
D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000097:blood
D008550:Melatonin