Changes in accelerometer-measured sleep during the transition to retirement: the Finnish Retirement and Aging (FIREA)...

Retirement is associated with increases in self-reported sleep duration and reductions in sleep difficulties, but these findings need to be confirmed by using more objective measurement tools. This study aimed at examining accelerometer-based sleep before and after retirement and at identifying trajectories of sleep duration around retirement.

The study population consisted of 420 participants of the Finnish Retirement and Aging study. Participants' sleep timing, sleep duration, time in bed, and sleep efficiency were measured annually using a wrist-worn triaxial ActiGraph accelerometer on average 3.4 times around retirement. In the analyses, sleep on nights before working days and on nights before days off prior to retirement were separately examined in relation to nights after retirement.

Both in bed and out bed times were delayed after retirement compared with nights before working days. Sleep duration increased on average by 41 min (95% confidence interval [CI] = 35 to 46 min) from nights before working days and decreased by 13 min (95% CI = -20 to -6 min) from nights before days off compared with nights after retirement. By using latent trajectory analysis, three trajectories of sleep duration around retirement were identified: (1) shorter mid-range sleep duration with increase at retirement, (2) longer mid-range sleep duration with increase at retirement, and (3) constantly short sleep duration.

Accelerometer measurements support previous findings of increased sleep duration after retirement. After retirement, especially out bed times are delayed, thus, closely resembling sleep on pre-retirement nights before non-working days.