Sensitive Circadian Clocks

 ...it works to regulate the daily routines of these patients, who are often found to have more sensitive circadian clocks. Disruptions in sleep and routine may spur bouts of mania or depression, says Frank, a psychiatry and psychology professor at the University of Pittsburgh School of Medicine.

A related study by biologist Colleen McClung, PhD, further elucidated the relationship between the circadian system and bipolar disorder. McClung, a psychiatry professor at the University of Texas Southwest Medical Center, studied mice engineered to lack key circadian genes. She found that they behaved similarly to people in a manic state, exhibiting hyperactivity and shortened sleep cycles. *