Relationship between morningness-eveningness typology and cumulative fatigue or depression among Japanese male workers.

This study clarified relationships between morningness-eveningness typology and cumulative fatigue or depressive state in Japanese male workers. 959 male chemical factory workers answered a questionnaire that included the MEQ, SDS, CFSI, age, marital status, sleep indexes, life habits, and labor load. Logistic regression analysis was performed with SDS and CFSI as objective variables.