Further support for higher salivary cortisol levels in "morning" compared to "evening" persons.
We analyzed free cortisol daytime levels in a "3-days-7-samples-a-day" protocol in relation to morningness in 112 middle-aged male and female adults derived from the first year of data of the Trier Teacher Stress Study using a one-item proxy for the assessment of chronotype. First, log-transformed cortisol levels were analyzed by a repeated-measures approach controlling for relevant covariates. Results yielded an almost significant main effect of morningness (P=.06). Subsequent within-day analyses, additionally controlling for awakening time, resulted in (marginally) significant main effects of morningness at Day 1 (P=.06) and Day 3 (P=.05) and a significant interaction of sample-by-morningness at Day 2 (P=.04). In sum, the present data seem to corroborate the idea of higher daytime cortisol levels in morning relative to evening types in a sample of healthy middle-aged male and female adults.
Kudielka
Brigitte M
BM
Department of Theoretical and Clinical Psychobiology, University of Trier, Trier, Germany. kudielka@uni-trier.de
Bellingrath
Silja
S
Hellhammer
Dirk H
DH
D000328:Adult; D000367:Age Factors; D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007206:Individuality; D008297:Male; D008875:Middle Aged; D012463:Saliva / Q000378:metabolism; D012737:Sex Factors; D014851:Wakefulness / Q000502:physiology*
D006854:Hydrocortisone