LONGITUDINAL CHANGES IN DIARY-BASED AND LABORATORY-BASED SLEEP MEASURES IN HEALTHY OLD-OLD AND YOUNG OLD SUBJECTS - A 3-YEAR FOLLOW-UP

We report a longitudinal study of diary- and laboratory-based sleep me asures in 50 healthy elderly subjects followed prospectively over a 3- year interval. Our hypothesis was that ''old old'' subjects (aged 75 t o 87; n = 27) would show decline over time in measures of sleep qualit y, continuity, and depth, whereas ''young old'' subjects (aged 61 to 7 4; n = 23) were expected to show stability of outcome measures. Using analysis of variance-based planned contrast procedures, we found that this hypothesis was strongly supported for subjective sleep quality an d laboratory measures of sleep latency, sleep efficiency, wakefulness after sleep onset, and slow-wave sleep percent. These changes were acc ompanied by increased napping in the old old. However, there was no ch ange of habitual time in bed (total time or temporal placement of nigh ttime sleep), daily social rhythms, or sleep apnea. Change in medical burden scores did not correlate significantly with change in sleep eff iciency or other outcome variables in the old old. Intervention design ed to slow age-dependent decreases in sleep quality, continuity, and d epth is discussed. The current results are representative of healthy e lderly; sleep would probably deteriorate earlier and more quickly in e lderly with more serious health problems and heavier medication use.