ABSTRACT
Several lines of evidence suggest direct relationships between sleep and biological rhythms and the pathophysiology and treatment of patients with bipolar disorder (Fig. 1). First, the longitudinal course of bipolar disorder is characterized by its periodic, or cyclic, nature. Second, an integral part of this periodicity is a marked divergence of sleep propensity according to the phase of the disorder (ie, a decreased need for sleep in mania or increased sleep tendency in bipolar depression). Third, a consistent clinical observation suggests that a sudden loss of sleep, in susceptible individuals, can precipitate an episode of mania. Fourth, these clinical observations and the desire for the understanding of the biological nature of this periodicity came during a time when the field of biological rhythms research was making dramatic discoveries into the biological underpinnings of internal biological ‘‘clocks’’ that regulated behavioral states. In the search for the pathophysiology of bipolar disorder, this led to studies of endogenous temperature, neuroendocrine, and motor activity rhythms in bipolar disorder. Clinically, this led to the development of therapies designed to alter biological rhythm function, such as ‘‘light therapy,’’ circadian phase manipulations, and biological and social rhythm therapy in patients with bipolar disorder. Fifth, after basic science discoveries regarding the nature and function of rapid eye movement (REM) sleep in the late 1950s and 1960s, there emerged in the field of electroencephalography (EEG) sleep research an interest in understanding the mysteries of sleep in healthy and pathological states. In psychiatry, this led to discoveries regarding the timing and quality of REM and non-REM sleep states in mood disorders
FIGURE 1 Sleep and biological rhythm contributing factors to the neurobiology of bipolar disorder.
