Duration of major depressive episodes and sleep architecture: an exploratory study

Growing evidence supports sleep-wake disruption as a mechanism involved in mood disorders pathogenesis. Duration of depressive episodes varies widely, and longer depressive episodes have been connected to worse outcomes. We aimed to explore if the length of depressive episodes is related to objective modifications of sleep features. 35 subjects, aged 18-70, hospitalized for the treatment of a major depressive episode, either unipolar or bipolar, underwent polysomnography, upon admittance. Objective sleep features were correlated with the length of the ongoing depressive episode, measured in months. Positive correlations were found between the duration of the depressive episode and wake percentage (r = 0.358, p = 0.035), N3 latency (r = 0.451, p = 0.014) and wake after sleep onset (r = 0.342, p = 0,44). Our findings show that individuals suffering longer depressive episodes can experience objectively worse sleep features, in terms of increased night wakefulness and delayed deep sleep.