Circadian rhythm in negative affect: Implications for mood disorders

Abstract

In humans, there is an endogenous, near 24-h (i.e., circadian) variation in mood with the best mood occurring during the circadian day and the worst mood occurring during the circadian night. Only positive affect, and not negative affect, has been shown to contribute to this circadian rhythm. We discovered a sharp circadian peak in negative affect during the circadian night coincident with a circadian trough in positive affect. These findings may help explain the association of depression with insomnia, the increased risk of suicide with nocturnal wakefulness, and the correlation between circadian misalignment and symptom severity in Major Depressive Disorder.

Keywords: Circadian; Mood disorders; Sleep.

Published by Elsevier B.V.

Figures

Figure 1:

Endogenous circadian rhythms in mood. Shown are z-scores (mean ± SEM) for the PANAS negative (□) and positive (○) affect scores, and POMS-B total mood disturbance (TMD) score (●). Data are plotted accordingly to circadian time in bin sizes of 60° (~4 hours) with the DLMO defined as 0°. Mixed model cosinor analyses (conducted on non-binned data) are shown for PANAS negative (---) and positive (– –) affect scores, and POMS-B TMD (—). The shaded rectangle corresponds to the participants’ average sleep timing prior to entering the laboratory. For all analyses, p