The effect of morning and evening lateness on salivary cortisol and melatonin

Abstract

The “bimodality” of the chronotype on the morning time scale is consistent with the idea of the multidimensional assessments of chronobiological individuality. The study aims to determine the salivary cortisol and melatonin daytime differences according to morning and evening lateness by SWPAQ. Data was collected from 700 respondents aged 17–24 by the online survey including Epworth Sleepiness Scale, and Sleep-Wake Pattern Assessment Questionnaire. Participants with extreme morning (M) and evening (E) lateness by SWPAQ (n = 80) collected saliva twice a day for cortisol and melatonin measurement. Inability to sleep in the morning (M-) have had significant cortisol decrease at the dark time and the lowest ESS score versus M+. Melatonin in M- and E-groups had a natural day–night curve. M+ and E+ had lower evening salivary melatonin. We concluded that participants with high M+ score have misbalance of cortisol and melatonin in the evening and increase of daytime sleepiness.