Sleep in the Prader-Willi syndrome. Clinical and polygraphic findings.

Nine patients with the Prader-Willi syndrome, ranging in age from 3 to 21 years, were examined clinically as well as studied in the sleep laboratory. They had striking disturbances of sleep-wakefulness patterns. All patients except one had the symptom of excessive daytime sleepiness. The most striking finding was the presence in five patients of rapid-eye-movement (REM) sleep occurring at sleep onset (SOREM). None of the patients had the condition of sleep apnea. One patient, however, demonstrated severe hypoventilation during REM sleep; the lowest value recorded for O2 saturation was 40%, with a consistent value below 50% for as long as ten to 15 minutes. Previous findings have indicated that the Prader-Willi syndrome is of hypothalamic origin. We hypothesize that both the SOREM and O2 desaturation findings in our patients with the Prader-Willi syndrome are also a result of hypothalamic changes.