Nocturnal Electrographic Features of Frequently Changing-Irregular Sleep-Wakefulness Rhythms

Abstract

Polygraphic characteristics of nocturnal sleep associated with frequently changing-irregular rest-activity schedules were investigated in healthy young adults. Two groups each of 12 male university students were classified according to a priori criteria as either: (a) controls who slept regularly for 7-8 hr at night or (b) whose retiring and arising times combined varied chronically ± 1.5 hr. Sleep was recorded during three consecutive 8-hr nocturnal periods at fixed clock times. Polygraphic indices generally reflected greater discontinuity and fragmentation associated with the nocturnal sleep in the young adults whose 24-hr rest-activity cycle tended to be frequently changing-irregular. The significantly: (a) larger absolute quantities of (i) transitional stage 1 sleep, (ii) intermittent wakefulness and (b) increased stage shifts provided some indication that the intrasleep cycle becomes disturbed when rest-activity schedules follow no predictable pattern in the everyday environment. Despite, or because of, the enforced hour (11:30 p.m.±30 min) for retiring, it is possible that the capacity to fall asleep had become phase-delayed among subjects with irregular rest-activity schedules who experienced more initial wakefulness (on average) before sleep onset stage 1. Finally, the recorded sleep perturbations associated with frequently changing-irregular schedules were extremely variable across nights and among individuals. This was especially pronounced on a nightly basis as reflected by significantly larger variability (SDs): (a) in the latency to sleep onset, for (b) total time asleep, (c) intermittent wakefulness, and (d) the ultradian (90-min) REM cycle. Variability (the SD) between individuals was also more substantial for these same polygraphic measures at statistically significant levels.

Additional information

Notes on contributors

John M. Taub

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.