Regular 48-hour cycling of sleep duration and mood in a 35-year-old woman: Use of lithium in time isolation

At least 20 cases of regularly occurring 48-hr mood cycles have been reported previously (Jenner et al. 1967; Kupfer and Heninger 1972; Gelenberg et al. 1978; Doerr et al. 1979; King et al. 1979; Frank and Harrer 1980; Paschalis et al. 1980; early cases reviewed in Bunney and Hartmann 1965; Sitaram et al. 1978). The disorder sometimes begins with longer, more irregular mood cycles that shorten progressively until a regular 48-hr pattern is established (Wiesel 1927; Doerr et al. 1979; Paschalis et al. 1980). In some cases, the onset of symptoms coincides with pregnancy (Pfanner 1930) or with a traumatic event, such as a head injury (Jenner et al. 1967) or a stroke (Scheiber 1901). The mood swings may be either unipolar or bipolar, of greater or lesser severity, but they nearly always exhibit remarkable regularity in timing. Patients typically switch between manic and depressive mood during each sleep period, seldom if ever missing a day. If untreated, the cycles may persist for many years, even decades. The intriguing regularity of the mood alternations in these cases provides a valuable opportunity to study the biological concomitants of affective disorders, and particularly suggests involvement of the circadian timing system in these disorders. Accordingly, we have performed an intensive evaluation of a previously undescribed patient exhibiting 48-hr mood cycles, paying particular attention to characteristics of sleep and other circadian rhythms before and during lithium treatment.