Is insomnia a disease of slow-wave sleep?

The aim of this paper is to examine if a disturbance of slow-wave sleep may partly account for the imbalance between waking and sleep observed in insomnia. 40 normal subjects and 40 insomniacs were recorded in the laboratory. No direct interregulation appeared between total sleep and REM sleep on one hand, and between slow-wave sleep and REM sleep on the other. Slow-wave sleep, however, was linked to the waking-sleep imbalance, as low values of stages 3 and 4 were statistically associated with low total sleep duration. The reduction of slow-wave sleep could not merely be attributed to an increased pressure of wakefulness. Our results indicate that it represents probably a disturbance in itself, perhaps related in some cases to a precocious senescence of sleep, but do not account alone for all sleep disturbances.