Transcranial bright light exposure via ear canals does not suppress nocturnal melatonin in healthy adults--a single-blind, sham-controlled, crossover trial.
We investigated whether transcranial bright light (TBL) affects nocturnal melatonin and cortisol secretion in sham-controlled crossover trial. Young healthy adults were exposed in random order to 24 minutes of TBL or sham exposure via ear canals at 01:10 h. Saliva and urine samples were collected hourly between 21 h-03 h and 06 h-09 h. There were no significant differences in melatonin or cortisol concentrations between TBL and sham exposures at any sampling point indicating that TBL via ear canals does not suppress nocturnal melatonin secretion. Thus, non-visual effects of TBL are mediated via a pathway not involving melatonin suppression.
Institute of Health Sciences, University of Oulu , Oulu , Finland .
Heidi
H
Jurvelin
Timo
T
Takala
Lilli
L
Heberg
Juuso
J
Nissilä
Melanie
M
Rüger
Juhani
J
Leppäluoto
Seppo
S
Saarela
Olli
O
Vakkuri
D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D018592:Cross-Over Studies; D004424:Ear Canal / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D012463:Saliva / Q000378:metabolism; D016037:Single-Blind Method; D055815:Young Adult
D008550:Melatonin; D006854:Hydrocortisone
Circadian rhythm; cortisol; ear light; melatonin; opsins; saliva