The overarching aim of the study is to clarify the nature of rhythm abnormalities in bipolar disorder and, especially, their relation to clinical state. We propose to do this in the context of a randomized intervention protocol in which half of the subjects will receive a treatment aimed at rhythm regularization. We expect to study individuals with a range of circadian and sleep-wake abnormalities, social rhythm disturbances, and circadian type and to examine the extent to which these parameters predict subjects' clinical outcomes. Since one half of the subjects will receive IPSRT as part of their treatment regimen (with increasing regularity of social routines as a goal of treatment), we will be able to examine the extent to which changes in social rhythm regularity and sleep quality are associated with clinical and functional improvement and whether these outcomes are mediated by changes in endogenous circadian rhythms.