A Daytime Nap May Contribute to Altered Emotional Processing in Depression

A study published in the Journal of Affective Disorders found that daytime REM sleep influences modulating perception of emotional faces among individuals with depression, which may contribute to the development of altered emotional processing.

The literature has indicated an association between REM sleep abnormalities and depression. Evidence suggests that sleep disturbances predispose an individual to develop and sustain mood disorders, leading some scholars to propose that alterations in sleep physiology may contribute to abnormal emotional processing and social dysfunction, indicators typical of depression. However, this assertion has not yet been rigorously tested.

Esther Yuet Ying Lau, PhD, of The Education University of Hong Kong and the Department of Psychiatry, Queen Mary Hospital, Hong Kong, and colleagues conducted a study of 46 individuals with major depressive disorder (MDD) and 66 age- and education- matched controls without depression.  Subjects completed an emotional face perception task both before and after random assignment to 1 of the following intention-to-treat conditions: a 30-minute nap, a 90-minute REM nap, or a period of wakefulness. Given the well-documented onset of REM at approximately 33 minutes of sleep, the differing nap conditions allowed the investigators to isolate the role of REM in affecting mood. Subjects were characterized into as-treated conditions, which included the above 3 categories as well as a 90-minute non-REM nap.  Data were analyzed using repeated measures multivariate analysis of covariance (MANCOVA).

The authors found a significant increase in the intensity rating of angry faces only after a 90-minute REM nap among subjects with MDD. Furthermore, high-intensity rating of angry faces and proportion of REM sleep were significantly correlated in this group (P=.035). They did note, however, that the effects observed during daytime napping may not reflect the effects of nighttime REM sleep in depression.

The investigators wrote, “This study underlines sleep as a core neurophysiological process exerting a potential influence in the socioaffective-cognitive deficits of depression, and implies that sleep health should be taken into consideration in clinical assessment and therapeutic approaches for social dysfunctions in depressive and potentially other affective disorders.”

Reference

Lau EYY, Lau KNT, Chan CS, et al. Effects of REM sleep during a daytime nap on emotional perception in individuals with and without depression [published online September 12, 2019]. J Affect Disord. doi.org/10.1016/j.jad.2019.09.058