Background. An association between social rhythm disruption (SRD) and onset of manic episodes has recently been observed. Whether other types of bipolar (depressive and cycling) or unipolar depressive episodes are similarly related to SRD is unclear, as is the association between severely threatening life events and onset of bipolar manic, depressed and cycling episodes.

Methods. Bipolar patients with purely manic (N = 21), purely depressed (N = 21) and cycling (N = 24) episodes, and 44 patients with recurrent unipolar depression, were interviewed with the Bedford College Life Events and Difficulties Schedule. The presence of severe and SRD events during the year prior to index episode onset was then determined.

Results. More manic than cycling and unipolar subjects experienced SRD events during 8- and 20-week pre-onset periods, and severe events during 20-week pre-onset periods. Controlling for age and prior number of episodes left most findings unchanged. An earlier finding of more manic subjects with SRD events in an 8-week pre-onset versus control period was also replicated.

Conclusions. It appears that manic onsets are influenced by stressful life events, especially those involving SRD, in a unique manner compared to onsets of other types of bipolar and unipolar episodes. Onset of bipolar cycling episodes, in contrast, seems to be relatively unaffected by SRD or severe life events. These findings refine the hypothesis that SRD may precipitate onset of affective episodes to be specific to manic onsets.