Effect of delayed sleep phase during university life on the daytime functioning in work life after graduation.

OBJECTIVE

To examine the effects of changes in sleep phase on the daytime functioning of new university graduates.

METHODS

Questionnaire data of university students (n = 745) and university graduates working full time (n = 360) were analyzed to explore sleep phase changes during this life stage. The newly graduated full-time workers (n = 117) were divided into 2 (bedtime at investigation: earlier/later) × 2 groups (bedtime at one year prior to investigation: earlier/later), and depressive symptoms and health-related quality of life were compared among groups.

RESULTS

New university graduates experienced ~1 h of sleep phase advancement and shortened time in bed compared to one year before investigation. In addition, those who experienced such sleep changes showed larger daytime dysfunction.

CONCLUSION

Prevention of extreme sleep phase delay during university days might be helpful for students' adaptation to work environment after graduation.