Sleep deprivation effects in older endogenous depressed patients

In a drug-free group of 15 older endogenous depressed inpatients, all-night sleep deprivation (SD) was associated with a significant decrease in Hamilton depression scores and in Profile of Mood States self-ratings of depression. Six of 15 patients (40%) were responders to SD, as evidenced by greater than or equal to 30% improvement in Hamilton ratings. While symptomatic improvement was short-lived (8 of 15 patients worsened after 1 night of recovery sleep), five patients showed further improvement after 1 night of recovery sleep. The final two patients had an increase in Hamilton ratings after sleep deprivation, with a return to baseline values after 1 night of recovery sleep. Responders (but not nonresponders) showed significant improvement in sleep latency, sleep efficiency, and slow wave sleep during recovery sleep (as did controls). The SD Hamilton depression rating (at 9 a.m. after all-night sleep deprivation) showed a significant inverse correlation with the increase in slow wave sleep (SWS) minutes and in SWS % from baseline to first recovery night. Responders also had significantly larger increases in SWS minutes than did nonresponders (53.8 vs. 7 minutes). Similarly, the % change in Hamilton depression ratings was predicted by baseline Stage 4 sleep. These findings suggest that there is a mutual interaction between the process of sleep regulation and the symptoms of depression. They also confirm a prediction from the two-process model of sleep regulation--namely, that improved sleep initiation and maintenance and increased SWS, attained by SD, are associated with clinical improvement.