Individuals with bipolar disorder often report that sleep disturbances are an early sign of manic episodes, and sometimes of depressive episodes. In this paper we studied whether sleep disturbances indeed occurred in the two weeks just preceding manic and depressive episodes in eight individuals with bipolar disorder.

Study participants were instructed to wear a wristwatch that was collecting actigraphy data (movement data) for 6 months. Sleep disturbances, such as shorter sleep duration and lower sleep efficiency, were calculated based on the actigraphy data for each individual separately. Participants also filled out daily and weekly questions on mood for half a year.

The results showed that most individuals had sleep disturbances in the two weeks preceding manic and depressive episodes. Individuals differed in what type of disturbances they had. However, sleep disturbances also occurred during periods in which participants’ mood symptoms were relatively stable. Thus, sleep disturbances were not always followed by manic or depressive episodes. When one would use sleep disturbances to signal upcoming mood episodes in this specific sample, this may have led to some false alarms. When interpreting the results, one should bear in mind the small sample size.

The study illustrates the individual differences in the type of sleep disturbances in the period before mood episodes. Based on the results, we would not advise to conduct a larger study to examine whether sleep disturbances (as measured with actigraphy) are reliable early warning signals of upcoming mood episodes.