Effects of age on delta and REM sleep parameters

Abstract

Sleep EEGs were evaluated in 24 men without medical and psychiatric disease segregated into 3 age groups: 21–30, 31–40, and 51–70 years of age. Sleep was evaluated by 3 different methods: traditional sleep stage scoring, computer-assisted delta and rapid eye movement (REM) quantification, and power spectral analysis. Analysis of manually scored sleep variables revealed that age-related changes in sleep were most pronounced in the oldest age group (51–70). Older subjects spent more time awake, had low sleep efficiency and sleep maintenance, displayed a decreased REM latency, and spent less time in delta sleep. Computer quantification further confirmed that the largest drop in delta activity occurred between the 21–30 and the 31–40 year olds. The largest decrease in delta activity occurred to the greatest extent during the first 100 min of sleep (NREM period 1), and was characterized by a shift in the spectral distribution of power towards higher delta frequencies. Total nighttime REM was increased in the 31–40 year-old group as compared to older and younger subjects. This unexpected non-linear trend may reflect a progressive tendency toward ‘lightening’ of sleep with increasing age. These studies further suggest that the effects of aging should be incorporated into models aiming at explaining the physiology of sleep.