Alpha-NREM sleep distributed across the 24-hour day in a legally blind elderly male

Abstract

A 77-year-old married man was evaluated in our Sleep Evaluation Center for a 6-month history of excessive daytime sleepiness. By reported history and a 2-week sleep diary, he showed a polyphasic sleep-wake rhythm, which, by itself, is not unusual in this age group (Tune, 1969a,b; Webb 1969; Miles and Dement 1980). However, 2 consecutive nights of polysomnography, followed by a Multiple Sleep Latency Test (MSLT), revealed a continuous well-formed alpha rhythm coincident with all NREM sleep recorded. Except for a 40-second fragment on the second night of recording, REM sleep was absent. Delta sleep was the predominant form of NREM sleep recorded in this patient, and it was recorded during the second half of both nights and throughout all four daytime naps (MSLT). To our knowledge, this is the first case description of a sleep-wake rhythm that shows not only a breakdown in the regulation of sleep and waking as distinct states, but also a redistribution of electroencephalographic (EEG) sleep architecture across the 24-hr period.