In agreement with the above findings, spectral analyses of the sleep EEG of healthy individuals, patients with UARS, and patients with OSAS have shown a similar dichotomy of results.9 Central leads on OSAS patients, compared to control subjects, present an important anomaly. They show a complete destructuring of sleep with a significant decrease in Δ power, which often is considered an index of sleep homeostasis. Impairment is seen in other EEG bands without significant increases in the α and β bands.9 In opposition, UARS patients present a comparatively high continuous power in the α and Δ EEG bands. This increase in absolute power is seen in successive sleep cycles throughout the night. Δ power, which may be related to the “need (or pressure) to sleep,” does not seem to decline throughout the night as in healthy subjects. The pressure still exists at the end of the night in UARS subjects, despite a substantial amount of Δ power in the sleep cycles during the night, which is a major difference compared to OSAS patients. The significant increase in α power in UARS patients, which is not present in OSAS patients, suggests that the cortex is continuously challenged and is in an arousal status.