Spring and autumn daylight saving time changes: studies of adjustment in sleep timings, mood, and efficiency.

Abstract

Various aspects of adjustment to Daylight Saving Time (DST) changes were investigated using two Spring and two Autumn studies. After both Spring and Autumn DST changes, although adjustment of times of retiring and falling asleep appeared to be instantaneous, waking times took up to a week to adjust. Other analyses suggested that beneficial effects on mood on awakening and perceived sleep quality might appear for much of the week after an Autumn DST change, but predominantly detrimental effects on mood after a Spring one. Performance on a calculations test at 0830 h was significantly enhanced after an Autumn DST change, though this was probably due to the enhancement in mood resulting from the change, rather than to simple lack of adjustment of the performance rhythm. Examination of individual differences in DST adjustment produced results that were consistent with those from previous studies in the shift-work and jet-lag areas, confirming the usefulness of DST changes as a vehicle for studying general problems of adjustment to changes in schedule.