Abstract
Background: Sleep health is a significant risk factor for incident depression. Much less is known about the impact of sleep health on the course of depressive symptoms in those who have already developed the disorder. The present study used longitudinal data of individuals with a depression diagnosis from the UK Biobank to analyse sleep health as a potential predictor for the course of depressive symptoms. The hypothesis was that better sleep health would predict a milder course of depressed mood and loss of interest.
Methods: Self-reported insomnia symptoms, sleep duration, chronotype and daytime sleepiness were assessed as predictors at baseline. Depressive symptoms were self-reported and assessed at baseline and at follow-up, 8.76 ± 3.00 years after the baseline assessment. Linear regression models were calculated for each outcome variable.
Results: The study comprised 4817 participants. Frequent insomnia symptoms and daytime sleepiness predicted a worse course of depressed mood (insomnia: β = 0.31 ± 0.10, p = 0.002; daytime sleepiness: β = 0.45 ± 0.11, p < 0.001) and loss of interest (insomnia: β = 0.30 ± 0.11, p = 0.005; daytime sleepiness: β = 0.32 ± 0.11, p = 0.003). On the contrary, early chronotype (β = -0.27 ± 0.10, p = 0.008) predicted a milder course of loss of interest.
Conclusion: Our findings suggest that sleep health variables have a significant impact on the course of depressive symptoms in a sample with clinically diagnosed depression. Future research may investigate the add-on effects of sleep health improvements in patients with depression receiving guideline-concordant treatment.