Discrepancy between subjective and objective sleep in patients with depression

The literature investigating the relationship between objective and subjective sleep in depressed patients is limited and the results are inconsistent. Furthermore, many factors that influence the aforementioned relationship have not been investigated. The present study was carried out to clarify the characteristics of self-estimation of sleep in depressed patients. Sleep was estimated concurrently using a sleep log and polysomnography for 5 consecutive days to investigate the relationship between subjective sleep estimation and objective sleep estimation in 23 patients with major depression (Diagnostic and Statistical Manual of Mental Disorders, 3rd edn, revised; DSM-III-R). Factors related to a discrepancy between both types of estimation were identified. The subjective total sleep time showed a significant, but moderate, positive correlation (correlation coefficient: 0.63) with the objective total sleep time. The degree of discrepancy was significantly correlated with various objective sleep variables and severity of depression. In the underestimation group in which the subjective total sleep time was shorter than the objective total sleep time, the objective total sleep time and slow-wave sleep time were shorter, age was greater and the extroversion score (Maudsley Personality Inventory) was lower than in the overestimation group in which the subjective total sleep time was longer than the objective total sleep time. The data suggest that subjective sleep estimation in depressed patients is influenced by their objective sleep, severity of depression, age and personality.