Marta Jackowska, Lydia Poole

This study investigated whether sleep problems, sleep duration and a combination of short or long sleep with sleep problems were predictive of depressive symptoms six years later. Participants were 4545 men and women aged 50 years or older from the English Longitudinal Study of Ageing. Sleep problems were indexed through self-report enquiring about the most frequent insomnia symptoms including difficulties falling asleep, waking up several times a night and waking up in the morning feeling tired. Sleep duration was ascertained by asking about average sleep in the weeknight. Depressive symptoms were measured with the Center for Epidemiologic Studies Depression scale. Sleep problems were predictive of elevated depressive symptoms at follow-up (odds ratio [OR] = 1.36, 95% confidence interval [CI] = 1.19-1.56). When explored separately, waking up in the morning feeling tired (OR = 1.71, 95% CI = 1.24-2.37) followed by difficulties falling asleep (OR = 1.49, 95% CI = 1.06-2.11) were also predictors of future depressive symptoms. Compared to optimal duration, short (OR = 1.90, 95% CI = 1.34-2.71) but not long sleep hours were also linked to elevated depressive symptoms. Participants reporting short sleep hours combined with high sleep problems also had an elevated risk of depressive symptoms six years later (OR = 1.85, 95% CI = 1.15-3.00). Long sleep combined with high sleep problems was not predictive of depressive symptoms. Short and disturbed sleep and their combination increase the risk of future depressive symptoms in older adults.