A SCHIZOPHRENIC PATIENT WITH AN ARRHYTHMIC CIRCADIAN REST-ACTIVITY CYCLE

A haloperidol-treated patient with chronic schizophrenia had a near-ar rhythmic circadian rest-activity cycle, whereas rhythms of 6-sulphatox y-melatonin and core body temperature were of normal amplitude and pha se-advanced. Sleep electroencephalography measured throughout a 31-h ' constant-bedrest' protocol revealed a phase-delayed sleep-wake propens ity cycle, low sleep continuity (ultradian 'bouts'), and very little s low-wave sleep and slow-wave activity (0.75-4.5 Hz). Switching treatme nt to the atypical neuroleptic clozapine improved both the circadian o rganization of the rest-activity cycle and the patient's clinical stat e. This observation can be conceptualized in terms of the two-process model of sleep regulation. High-dose haloperidol treatment may have lo wered the circadian alertness threshold, whereas clozapine augmented c ircadian amplitude (perhaps through its high affinity to dopamine D4 a nd serotonin 5HT7 receptors in the suprachiasmatic nuclei). Measuremen t of the circadian rest-activity cycle may be a useful non-invasive me thod to follow functional consequences of neuroleptic treatment. (C) 1 997 Elsevier Science Ireland Ltd.