A categorical approach to changes in latency, awakening, and sleep length in older subjects.

Sleep latencies, within night awakenings, and lengths of sleep of 50- to 70-year-old males and females were analyzed using a categorical procedure. Subjects were assigned to qualitatively distinct categories. The data indicate that tendencies toward sleep disturbances along these dimensions are independent but increasing across this age range. There were disproportionately large numbers of females with long latencies and males with higher amounts of awakenings.