• Wrist motor activity and sleep were monitored longitudinally in 15 rapidly cycling and 52 nonrapidly cycling manicdepressive patients. The majority of patients experienced one or more consecutive 48-hour sleep-wake cycles (alternate nights with no sleep) when they switched out of depression into mania or hypomania. During a depressive phase, nine rapidly cycling patients were asked to simulate a 48-hour sleep-wake cycle by remaining awake for 40 hours (one night's total sleep deprivation). Eight switched out of depression, and seven were rated as manic or hypomanic; indicating that sleep loss (such as occurs with spontaneous 48-hour sleep-wake cycles) may help to trigger switches from depression to mania. The 48-hour sleepwake cycles in patients may depend on a mechanism that is normally present in all humans, since normal persons also spontaneously experience near-48-hour sleep-wake cycles in certain experimental conditions.
Wehr TA, Goodwin FK, Wirz-Justice A, Breitmaier J, Craig C. 48-Hour Sleep-Wake Cycles in Manic-Depressive IllnessNaturalistic Observations and Sleep Deprivation Experiments. Arch Gen Psychiatry. 1982;39(5):559-565. doi:10.1001/archpsyc.1982.04290050037008