| Abstract: | Apart from pharmacotherapy and biological conceptualisations, the cognitive theory and its therapeutic approach are likely the most used in the conceptualization and the treatment of major depression. The cognitive model attempts to explain how certain factors activate a dysfunctional cognitive structure. As such, the cognitive therapy focuses on the modification of negative and depressive cognitive distortions. Despite a success rate of approximately 66%, a significant proportion of patients (30%) suffer a relapse within one year of treatment. This suggests that the cognitive approach is not sufficient to explain the development, maintenance, remission and relapse of a major depressive episode. It is proposed here that sleep and chronobiological factors should be taken into consideration in order to improve the understanding of major depression and to maximize the chances of complete remission in those who suffer from this disorder. Indeed, both research and clinical reports have revealed that major depression is accompanied by sleep disruptions. More specifically, three types of problems have been identified: (1) Sleep discontinuity (reduced total sleep time, increased sleep latency, increased awakenings, reduced sleep efficiency); (2) decreases in slow wave sleep (SWS); (3) changes in rapid eye movement (REM) sleep characteristics (decreased REM latency, increased REM density, increase in the length of the first REM period and in the quantity of REM sleep). Of particular interest is the observation that, when the depressive symptoms disappear, sleep improves. Recent research, however reveals that certain sleep abnormalities, namely short REM latency and reduced SWS, are more robust or trait-like and are indicators of an increased risk of relapse. Furthermore, other studies suggest that the presence of these sleep abnormalities may facilitate the onset of depression. Models of sleep-wake regulation which have attempted to explain the sleep characteristics of depression are reviewed. These point to underlying chronobiological factors such as phase advances of circadian rhythms and suggest that such factors are responsible for the manifestation of the sleep disturbances observed in major depression. Fortunately, techniques that improve sleep quality and resynchronize the biological rhythms are available. Sleep hygiene maximizes sleep habits that facilitate normal sleep, particularly sleep initiation, sleep continuity and length of sleep. On the chronobiological side, bright light exposure and sleep schedule manipulations can resynchronize sleep periods with the appropriate circadian phase. It is thus proposed that sleep recordings, namely polysomnography, which have recently become more readily available (particularly with ambulatory devices), be used to select adequate treatment, and to support decisions regarding treatment duration. Similarly, sleep hygiene and chronobiological treatments should be integrated in the treatment of major depression. This article concludes by proposing a hierarchical model of interventions that combine polysomnography and chronobiological techniques with the classic cognitive approach to major depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
