Sleep disturbances in the prodromal phase of mood episodes in patients with bipolar disorder: a replicated single-case design

This study aims to examine whether objectively measured sleep disturbances occur in the prodromal phase of mood episodes in patients with bipolar disorder. Thirteen patients with bipolar disorder were studied using a replicated single-case time-series design for 180 days with continuous actigraphy and a daily Ecological Momentary Assessment of mood symptoms. Eight patients were suitable for analysis. Sleep variables (sleep onset, sleep offset, sleep efficiency, sleep duration, sleep onset latency, minutes awake after start of sleep, composite phase deviation) were estimated using actigraphy. Mean shifts and extreme values in the data were assessed using change point analysis and statistical process control. Mean shifts and extreme values in sleep were studied in the two weeks preceding depressive episodes and manic episodes. Changes in sleep were observed in the two weeks preceding mood episodes in two out of three individuals with a manic episode and in four out of five individuals with a depressive episode. There were individual differences in the type of sleep variables that showed change. However, these changes did not occur at a higher rate than during phases in which patients were stable. The order of change in sleep and EMA assessed mood could not be disentangled. The current study illustrates the heterogeneity of the type of sleep disturbances as assessed with actigraphy in the weeks before mood episodes.