Researcher David Harper and his colleagues monitored two key components of the circadian system — the rise and fall of core body temperature and the waxing and waning of spontaneous motor activity — in 38 dementia patients with either Alzheimer’s disease or another form of dementia, frontotemporal degeneration. They found that body temperature reached its peak much later in the day in the Alzheimer patients than it did in control subjects. People with frontotemporal degeneration exhibited a much different pattern. Their activity levels reached a peak earlier in the day than in control subjects while their body temperature rhythms appeared normal. The method could lead to more effective ways of treating the circadian sleep disorders that accompany all forms of dementia — disturbances so overwhelming that they often lead to the institutionalization of patients.