This review considers evidence that sleep and circadian rhythms are disturbed in bipolar patients during both mood episodes and periods of remission. Indeed, bipolar patients display disturbances of subjective and objective circadian markers, in sleep continuity, and in cortisol and melatonin secretion. Better characterization of sleep and circadian rhythms can improve personalized assessment and help identify treatment focusing on normalizing these disturbances. Therapeutic applications of chronobiology in bipolar disorder, such as specific psychosocial intervention, light therapy and physical exercise are described. The study of sleep and circadian rhythms opens innovative avenues in research concerning the pathophysiology of bipolar disorder, including the possible discovery of biomarkers, and may lead to a better understanding of genes role in bipolar disorder regarding associations of some circadian genes polymorphisms with bipolar disorder.