Intra-Night Sleep Perception in Patients with Sleep Disorders

Abstract

Measured and rated sleep differ in normal sleepers and even more in patients with sleep disorders. The study aimed to asses sleep/wake perception in electrophysiologically defined sleep in patients with sleep disorders. 117 consecutively referred patients (75 females), median age 50.3 years, range 20–73 years) with various sleep disorders were randomized for one induced waking, either out of stage 2 (S2) or REM sleep, as part of a clinical routine polysomnography. Patients were classified as either non-sleepy (Epworth Sleepiness Scale score ESS ≤ 10) or sleepy (ESS ≥ 11). The most frequent diagnoses of non-sleepy patients were insomnia and RLS, while sleepy patients suffered predominantly from OSAS, hypersomnia and insufficient sleep syndrome. Subjects were deliberately aroused once, either out of consolidated stage 2 sleep (n = 66) or REM sleep (n = 51) and asked for sleep/wake perception (sleep/wake and related questions). While 81 (69.2%) of the subjects estimated that they had been sleeping or dozing before they were aroused, 36 (30.8%) reported that they had been awake. Awake ratings were significantly more frequent for S 2 (45.5%) than for REM sleep (11.8%). The difference between sleep states was most pronounced for insomniacs (58.1% awake ratings in S2 vs. 5.3% in REM sleep). Mismatches between measured sleep and perceived state are quite frequent, with a greater disparity for S2 than for REM sleep, especially in insomniac patients. We suggest that state judgement is contingent not only on the state of the sleep regulating system but also on cognitive processes associated with processing of external and internal stimuli, and dreaming.