Phenomenology of sleep among insomniacs and good sleepers: Wakefulness experience when cortically asleep.

Twenty-five insomniacs and 10 good sleepers slept in a laboratory for two consecutive nights, and for an intervening daytime nap session. Each subject was awakened at the end of the 10th consecutive epoch of initial Stage 2 sleep and was asked to report on her/his experience of sleep or wakefulness. Insomniacs reported less sleep experience in both the night and nap sessions. Clinical experience and recent research suggest that some insomniacs may experience and/or report the presence of sleep differently than others. For example, subjective insomniacs are now distinguished from psychophysiological insomniacs by their persistent and apparently honest reports of disturbed sleep despite polygraphic evidence of relatively normal sleep (cf., "The Diagnostic Classification of Sleep and Arousal Disorders, " 1979). Moreover, in laboratory studies subjective overestimation of sleep-onset latency by insomniacs is commonly observed (e.g., Carskadon et al., 1976), even when subjective insomniacs are excluded (e.g., Bixler, Kales, Leo, & Slye, 1973). Even more compelling was Slama's (cf., Borkovec, 1979) finding that insomniacs, awakened during a nap session from Stage 2 sleep, reported the presence of sleep significantly less often than good sleepers. The basic purpose of the present study was to replicate this effect and to assess whether the same phenomenon occurs during night sleep. Subjects