Lm. Ghali et al., TEMPORAL SHIFTS IN PEAK DAILY ACTIVITY IN ALZHEIMERS-DISEASE, International journal of geriatric psychiatry, 10(6), 1995, pp. 517-521
Clinicians caring for Alzheimer patients have observed that some indiv
iduals show increased agitation, restlessness and confusion in the lat
e afternoon, evening or at night. This has popularly been named 'sundo
wning' or 'the sundowning syndrome'. Despite its obvious clinical impo
rtance, little research has been conducted to investigate abnormal act
ivity patterns in patients with Alzheimer's disease. In this study, re
st-activity patterns were examined using an electronic monitor with a
movement sensor. Eighteen patients diagnosed with Alzheimer's disease
were monitored for 48 consecutive hours each. Analyses indicated that
some subjects showed increased activity around the time of sunset, and
that these individuals were most likely to be in the middle stages of
the disease. Subjects in the early stages of the disease showed peak
activity before sunset, while those in the late stage showed peak acti
vity after sunset. This progressive phase shift with increasing years
of illness is a previously unreported phenomenon which may offer an ex
planation for the 'sundowning syndrome'.