Greater eveningness is associated with a larger gap between self-reported sleep need and weekday sleep duration.
Most adults are recommended to get 7-8 hours of sleep per night, but individual sleep needs vary.
Increasing age is linked to a preference for earlier sleep times (greater morningness).
No significant associations were found between and self-reported sleep need or weekday sleep duration after adjusting for age.
Evening types reported a similar sleep need and duration as morning types, despite accumulating sleep debt during the week.
On weekends, evening types compensated for lost sleep with longer sleep duration and later wake times.
Simplified
Most recommendations are that adults should obtain 7-8 hours of sleep per night, although there are individual differences in self-reported sleep need. (preference for early or late sleep timing), in combination with social demands, may affect the ability to obtain adequate sleep. This questionnaire study assessed perceived sleep need and self-reported sleep timing and duration during the week and on the weekend with respect to chronotype in visitors to the Museum of Science in Boston. Increasing age was associated with greater morningness. After adjusting for age, we found no significant association between chronotype and self-reported sleep need, or between chronotype and weekday sleep duration. However, we did find that greater eveningness was associated with a larger gap between self-reported sleep need and weekday sleep duration. On weekends, greater eveningness was associated with a longer sleep duration and greater extension of sleep, with the sleep extension achieved by later wake times. Together, these findings suggest that evening types accumulate a sleep debt during the week, despite reporting a similar sleep need and duration as morning types, and evening types then attempt to make up for that lost weekday sleep on the weekends. Studies of sleep need and sleep duration should take chronotype into account, and studies of chronotype may be confounded by the association between age and morningness, and must account for this potential confound in selection criteria and/or analysis.
Key numbers
41.85 ± 9.89 vs. 31.54 ± 12.68 years
Age Difference
Average ages of morning types vs. evening types.
17.5 minutes
Sleep Need Difference
Age-adjusted sleep need difference between evening and morning types.
0.86 hours
Weekend Sleep Duration Increase
Difference in weekend sleep duration for evening types.
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