Napping during major depressive episodes identifies a distinct Hypersomnolence phenotype

Abstract Study Objectives Prior studies have linked depression with napping, though findings remain inconsistent. Given that major depressive episodes (MDE) commonly involve sleep–wake and circadian disturbances, we hypothesized that daytime Napping during MDE reflects more pronounced sleep/circadian disruptions and a distinct clinical profile. Materials and methods We compared MDE patients with and without napping (MDE-NAP vs MDE), as well as unipolar and bipolar subgroups, using subjective and objective biomarkers, including actigraphy. Results The MDE-NAP group had more frequently hypersomnia (30.6% vs 8.2% p < 0,001), daytime sleepiness (73.1% vs 41.8%, p < 0.001), daytime fatigue (97.1% vs 88.5%, p = 0.042), family history of depression (68.2% vs 52.2%, p = 0.044), weight gain (42.2% vs21.6%, p = 0.006), and feelings of guilt (75.0% vs57.8%, p = 0.027). The unipolar napping group had greater weight gain (48.8% vs21.4%, p = 0.004) and more hypersomnia (26.1% vs3.4%, p < 0.001). The bipolar napping group were more frequently women (76.9% vs52%, p = 0.046), with more suicidal ideation (65.4% vs37.8%, p = 0.031), sad mood (73.1% vs43.1%, p = 0.019), hypersomnia (38.5% vs15.8%, p = 0.04), and guilt (61.9 vs35.1, p = 0.049). Regarding sleep scales, MDE-NAP had more hypersomnolence symptoms (HSI total score, p < 0.001), with higher frequencies of sleep inertia, daytime sleep, sleepiness, daytime dysfunction, and sleep attacks; and showed longer sleep duration (PSQI sleep duration, p = 0.025), and higher sleep efficiency (PSQI sleep efficiency, p = 0.015). Actigraphy did not reveal significant between-group differences in the subsample with usable recordings (N = 90). Conclusions Daytime napping during major depressive episodes appears to identify a distinct hypersomnolence phenotype with sleep-vegetative burden, supporting the systematic assessment of napping to guide personalized sleep- and circadian-based therapeutic strategies. This paper is part of the Sleep and Circadian Mechanisms in Mental Health Collection.