Ellen Frank of the University of Pittsburgh School of Medicine said bipolar disorder is highly influenced by the circadian system -- the body's internal clock and psychotherapy that focuses on practical lifestyle changes and can ease the symptoms of bipolar disorder.

Frank studied 175 adult patients with bipolar disorder and compared the effects of two therapies when combined with a common medical treatment for bipolar disorder -- usually lithium carbonate.

The study found that patients who participated in interpersonal and social rhythm therapy -- patients monitor the regularity of their daily routines -- in the earlier phases of the trial were able to go longer without a new episode of mania or depression than those who received clinical management -- which focuses on patients' mood symptoms and management of medication side effects.

The study found that patients who participated in interpersonal and social rhythm therapy in the earlier phases of the trial were able to go longer without a new episode of mania or depression than those who received clinical management.

The findings are bring presented today at the American College of Neuropsychopharmacology annual meeting in Boca Raton, Fla.