Is there evidence for social rhythm instability in people at risk for affective disorders?

Social rhythm disruptions are thought to be related to the etiology of affective symptoms. 'Hypomanic personality' and 'rigidity' are hypothesized to be risk factors for affective disorders. We examined whether people scoring high on such scales would demonstrate instability of social rhythms and sleep. In a short-term prospective diary study with one group factor, the following three groups were selected from a non-university student sample: 'bipolar risk' (scoring high on the 'Hypomanic Personality Scale'; n=56); 'Unipolar risk' (scoring high on the 'Rigidity Scale'; n=37); and a control group (scoring low on both scales; n=48). The participants completed ratings of their activities and sleep for 28 days. People at risk for bipolar disorders showed a lower regularity of daily activities than controls. Their sleeping pattern was not characterized by fewer but by more variable hours of sleep. The unipolar risk group did not differ from the control group at all. Despite some limitations, there is partial evidence for social rhythm and sleep irregularities in people putatively at risk for bipolar disorders. Further research is, however, needed to replicate and extend these results.