"It's time, you must wake up now".

Seven subjects who claimed to be able to awake accurately from sleep at a predetermined time were required to awake in the sleep laboratory at 03:30 and 05:30 on two separate nights. Eight of the 12 spontaneous awakenings were within +/- 20 min. from the target time, and 8 awakenings were from REM sleep. The two best performing subjects were tested for additional 7 nights in the laboratory but accuracy deteriorated considerably with only 2 awakenings within +/- 20 min. from target time. Approximately 50% of all awakenings, however, were from REM sleep. It is concluded that some individuals are able to awake at predetermined times and that this ability might be dependent on motivational level and the sleep stage.