No abstract

Summary Sleep disturbance is a core symptom of mood disorders. However, surprisingly little is known about the relationship between sleep quality and ambulatory daily mood, especially in mood‐disordered populations. We assessed ambulatory positive affect (PA) and negative affect (NA) 10 times daily for three consecutive days with the computerized experience sampling method among persons with major depression (n = 35), minor depression (n = 25) and healthy controls (n = 36). Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). Poorer sleep quality predicted lower ambulatory PA, even after accounting for the effects of diagnostic group and self‐reported anxiety. Conversely, sleep quality did not predict ambulatory NA once diagnostic group was accounted for. Analyzes of specific PSQI component scores indicated that poor subjective sleep quality and self‐reported daytime dysfunction were the sleep components most strongly tied to reports of low ambulatory PA. Impaired sleep quality may be responsible for reduced pleasurable experience in everyday life.

Objective Low resting respiratory sinus arrhythmia (RSA) levels and blunted RSA reactivity are thought to index impaired emotion regulation capacity. Major Depressive Disorder (MDD) has been associated with abberant RSA reactivity and recovery to a speech stressor task relative to healthy controls. Whether impaired RSA functioning reflects aspects of the depressed mood state or a stable vulnerability marker for depression is unknown. Methods We compared resting RSA and RSA reactivity between individuals with MDD (n=49), remitted depression (RMD, n=24), and healthy controls (n=45). ECG data were collected during a resting baseline, a paced-breathing baseline, and two reactivity tasks (speech stressor, cold exposure). Results A group by time quadratic effect emerged (F=4.36(2,109), p=.015) for RSA across phases of the speech stressor (baseline, instruction, preparation, speech, recovery). Follow-up analyses revealed that those with MDD uniquely exhibited blunted RSA reactivity, whereas RMD and controls both exhibited normal task-related vagal withdrawal and post-task recovery. The group by time interaction remained after covariation for age, sex, waist circumference, physical activity, and respiration, but not sleep quality. Conclusions These results provide new evidence that abberant RSA reactivity marks features that track the depressed state, such as poor sleep, rather than a stable trait evident among asymtomatic persons.