Abstract
Sleep structure in dementia is influenced by various factors, including the underlying cause and severity of dementia, the presence of somatic complications, the level of activities of daily living (ADL) and the patient’s age. The characteristics of sleep structure and the sleep-wake rhythm in elderly dementia patients, eleven bedridden patients and nine semi-dependents assessed by clinical dementia rating (CDR) were studied by comparing their night sleep polygraphs and records of day and night activity levels with those of normal elderly group. To examine the effect of social interactions on nocturnal sleep, activity levels were recorded for the twelve bedridden patients over a period of four consecutive days.
In dementia groups (N=20), the percentages of stage I sleep was significantly higher (P<0.01) and the percentages of stage II sleep, slow wave sleep and sleep efficiency index were significantly lower (P<0.01) than that in normal healthy elderly groups (N=10). In the bedridden groups (N=11), the percentages of stage II sleep and REM sleep were significantly lower (P<0.01) and the percentages of stage I sleep was significantly higher (P<0.01)than that in semi-dependent groups (N=9). Furthermore, DA (the daytime activity) and %DA (ratio of daytime activity to nighttime activity) decreased significantly in the dementia groups than normal healthy elderly groups and only a few cases in dementia groups showed a clear circadian rhythm of activity/rest.
Also, the sleep rate during nighttime for the bedridden patients (N=12) increased following social interactions. In particular, the sleep rate of patients who had a sleep rate of less than 40% for a standard night increased significantly after social and interactive exercises (P<0.01).
The observed changes in sleep structure and loss of circadian rhythm of activity/rest recognized in elderly dementia suggest the possibility of the dysfunction of a biological rhythm caused by functional and physiological changes in the brain. Moreover, manipulation of social and interactive exercises is a useful therapeutic method for the improvement of sleep disorder in bedridden patients deficient in social synchronizers who sleep poorly at night.
