Human circadian rhythm in serum melatonin in short winter days and in simulated artificial long days.
Serum melatonin rhythm was studied in 6 human subjects experiencing short winter days resembling light/dark (LD) 8:16 h and in 6 subjects exposed at the same time to a long, LD 16:8 h skeleton photoperiod, with 3 h of bright light in the evening and again in the morning; 4 out of the 6 subjects entrained to the simulated summer photoperiod within 3 days. In the synchronized subjects, the nocturnal melatonin signal was 3 h shorter than in those experiencing just winter days. The data indicate that humans are able to respond to environmental day length by forming a proper endogenous photoperiodic signal.
Buresová
M
M
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
Dvoráková
M
M
Zvolský
P
P
Illnerová
H
H
D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000097:blood*; D012621:Seasons; D013997:Time Factors
D008550:Melatonin