The free-running circadian rhythms of two schizophrenics.

Two chronic schizophrenic patients and a psychiatrist spent 21 days in an isolation unit. For the first 4 days they lived on normal time but thereafter the clock was removed and they were free-running. The psychiatrist followed the schedule set by the schizophrenics, one of whom spontaneously decided the times of retiring and rising while the other followed passively. The psychiatrist commonly retired some time later but without disturbing the schizophrenics, the mean duration of whose days was 23.7 h, distinctly shorter than is usual in healthy subjects. This was made up of an activity period of 11.77 h and a rest period of 11.94 h. Pulse rate and temperature were measured frequently throughout the waking hours and rectal temperature was monitored during sleep. Urine samples were also collected throughout the 24 h and were analysed for potassium, sodium, chloride, creatinine, phosphate, calcium and uric acid. Urinary and temperature rhythms followed approximately the activity rhythm, in both healthy and schizophrenic subjects. Pulse rate in the schizophrenics followed a rhythm with a period slightly less than that of activity, and in one schizophrenic showed a consistently early phasing. 11-hydroxycorticosteriods at the end of the observation showed a very early phasing corresponding to that of activity. The findings suggest that schizophrenics may have an abnormally short circadian period.