Sleep-wake cycles in multi-infarct dementia and dementia of the Alzheimer type.

We monitored by actigraphs minute-by-minute activity of 10 patients with multi-infarct dementia (MID), 15 patients with dementia of the Alzheimer type (DAT), and 11 control volunteers for eight consecutive 24-hour periods to assess sleep-wake cycles and sleep quality. MID patients had disrupted sleep-wake cycles associated with decreased sleep quality. In contrast, ambulatory DAT patients maintained a relatively normal sleep-wake cycle that did not differ significantly from controls. There was no correlation between the severity of intellectual deterioration and the degree of sleep-wake cycle disintegration in either group of dementia patients.