Associations between chronotype and salivary endocrinological stress markers

Abstract

Objectives: To investigate the effect of chronotype on salivary cortisol or salivary α-amylase (sAA).

Methods: From 108 male university students, saliva samples were collected in the afternoon (between 15:00 and 17:00). The salivary cortisol and sAA levels were determined with commercial kits. Chronotype was quantitatively evaluated using the Horne and Östberg Morningness-Eveningness Questionnaire. Subjects were categorized into morning types and evening types.

Results: The sAA levels were lower in the morning types than in the evening types. We found no significant difference in salivary cortisol levels between the two groups.

Conclusions: These findings suggest that the sAA levels may be associated with chronotype.