Academic journal article Indian Journal of Psychiatry

Effect of Depression on Sleep: Qualitative or Quantitative?

Academic journal article Indian Journal of Psychiatry

Effect of Depression on Sleep: Qualitative or Quantitative?

Article excerpt

Byline: Ravi. Gupta, Sushant. Dahiya, Manjeet. Bhatia

Background: The present study was designed to assess whether subjective sleep patterns differ between: (i) depressed patients and controls, and (ii) between subjects with different severity of depression. Based on available literature, it was hypothesized that sleep patterns must be different between the above mentioned groups. Materials and Methods: This study included 60 subjects with major depressive disorder and 40 subjects in the control group. Subjects with sleep disturbance secondary to any other factor, e.g ., medical illness, environmental factors, other psychiatric illness etc, were not included in the study. Depression severity was assessed in the subjects with depression with the help of Beck Depression Inventory II. Subjective sleep complaints were noted in the presence of a reliable informant, preferably bed partner. All the information was recorded in a semistructured performa. Statistical analysis was done with the help of SPSS v 11.0. The Chi square and Fisher exact tests were used for categorical variables; independent t-test and one way ANOVA were applied for numerical variables. Ordinal variables were analyzed using Mann Whitney U and Kruskall-Wallis tests. Results: Depression and control groups were similar in age ( P = 0.32) and gender ( P = 0.14) distribution. Subjects in the depression group had lesser total sleep time ( P = 0.001), longer sleep latency ( P = 0.001), frequent awakenings ( P = 0.04), greater wake-after-sleep onset and offset times (both P = 0.001), lesser sleep efficiency, and tended to wake up early (Mann Whitney U = 913.5; P = 0.05). Subjects with severe depression were different from the mild and moderate groups with regards to total sleep time ( P = 0.002), night-time sleep ( P = 0.007), and sleep efficiency ( P = 0.001) even when the three groups were comparable in age. Conclusion: Depression is associated with sleep disturbances, not only qualitatively, but also quantitatively. Sleep disturbance arises only after a critical level of depression is reached, and depression of varying severity may selectively affect different sleep parameters.

Introduction

Sleep disruption is a common feature of depression, manifesting itself as reduced total sleep time (TST), increase in sleep latency, and frequent awakenings during night-time sleep. Moreover, the sleep schedule usually changes during depression and, when subjectively asked, sleep is reported to be nonrestorative.[sup] [1]

Changes that occur in sleep during depression, may be confirmed objectively with the help of polysomnography. These studies demonstrate changes in sleep architecture, e.g ., decrease in slow wave sleep (SWS) and REM latency, increase of REM density, and frequent arousals.[sup] [2] One study suggests that the severity of depression affects the polysomnographic findings as severely depressed subjects show lesser amount of stage two and three sleep, shortest REM latency, and shortest REM cycle duration than mild depression and control groups. On the contrary, stage 2 and 3 sleep is increased in mild depression as compared to controls.[sup] [3] Thus, evidence demonstrates that sleep architecture is not uniformly influenced by depression of varying severity.

Depression is a stressful situation and it leads to hyper-arousal, which is positively correlated with the severity of depression.[sup] [4] The cognitive theory of insomnia suggests that insomnia and hyperarousal run in a vicious cycle, where each exacerbates the other.[sup] [5] This is further substantiated by the fact that stresses that are accumulated during the day, show their effect on the sleep during night.[sup] [6] Neurobiological markers of stress, e.g ., serum cortisol concentration, correlate with changes in sleep akin to those seen in depression.[sup] [7] Taken together, these proofs suggest that depression severity influences sleep architecture differently. …

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