To the Editor.—
The case report of Kales et al (Archives 179;36:650-651), which relates the successful treatment of narcolepsy with propanolol hydrochloride, deserves belated comment with respect to the control of respiration during sleep. The article implies that the episodes of central sleep apnea occurring during rapid eye movement (REM) sleep while the patient was taking methylphenidate hydrochloride were abnormal.As noted by Phillipson,1 such episodes are a normal accompaniment of REM sleep and should not be considered a part of the syndrome of sleep apnea. We are told that propranololtherapy REM sleep was "notably suppressed" and that sleep apnea was abolished. Propranolol is well known to interfere with normal sleep2 and the changes recorded here are interesting, but it should not be concluded from this that propranolol has had a more direct effect on the narcolepsy. The evidence of a therapeutic effect is indeed compelling, but the