Sleep in the Prader-Willi Syndrome

To the Editor.  —Dr Vela-Bueno and colleagues¹ suggest that their finding of sleep-onset rapid-eye movement periods (SOREMPs) in the nocturnal sleep in five of nine patients with Prader-Willi syndrome (PWS) was due to hypothalamic dysfunction. They failed to mention that a shortened REM sleep latency could result from chronic REM sleep deprivation due to REM sleep-related hypoventilation.If episodes of hypoventilation are more frequent or more severe in REM sleep, then the associated arousals will interrupt and reduce the amount of REM sleep. An SOREMP is one typical effect of REM sleep deprivation. We have previously reported a case in which hypoventilation did not result in apneic events but did produce severe oxygen desaturation associated with the hypoventilation during REM sleep.² This patient had SOREMPs (REM latencies of one and 11 minutes) on each of two nocturnal sleep recordings. Dr Vela-Bueno and associates' finding of severe hypoventilation and hypoxic