Observed behavior as a predictor of the response to sleep deprivation in depressed patients

Total sleep deprivation (TSD) in depressive patients is known to produce sudden changes in mood, but the factors involved in these mood changes are poorly understood. In this study the role of psychomotor activation was investigated by examining the relationships between baseline measures of activation and subsequent clinical response to TSD. Two methods were used to assess the degree of activation: global judgment (clinical ratings) and direct observation and registration of behavior (ethological methods). Behavioral and global assessments took place 1 day before TSD during a medication-free psychiatric interview. The amount of looking displayed during the interview was negatively correlated with the subsequent clinical response to TSD, while body- and object-touching hand movements showed a positive correlation. During switches from speaking turn and at the start of the patients' speaking turn, responders to TSD showed more hand movements than nonresponders. No relation was found between clinical ratings of the degree of psychomotor activation and the TSD response. Our data suggest that the clinical response to TSD may be predicted and therefore possibly mediated by dimensions of activation. For the detection of these dimensions, behavioral observation appears to be more suitable than global clinical judgment.