Alzheimer's disease (AD) is a brain disorder that affects a person's thoughts, memory, speech, and ability to carry out daily activities. With AD the loss of brain tissue that leads to loss of mental abilities may also disrupt the sleep/wake cycle, which may cause sleep problems, nighttime wandering, and agitation.
AD affects an estimated 4.5 million Americans, according to the National Institute on Aging at the National Institutes of Health. Alzheimer's disease is not a normal part of aging but the risk of developing it goes up with age. It usually begins after age 60 and the risk nearly doubles with every 5 years of age after age 60, according to the U.S. Surgeon General. Because of the "graying" of Americans, the number of Alzheimer's patients is expected to increase dramatically in the coming years.
The amount of sleep disruption in AD patients usually depends on the stage of their disease. Patients in the early stages of AD may sleep more than usual or wake up disoriented. As the disease progresses, patients may begin to sleep during the day and awaken frequently throughout the night.
Patients with more advanced AD rarely sleep for long periods. Rather, they doze irregularly throughout the day and night. Circadian rhythms - daily cycling of body temperature, sleep, wakefulness, and metabolism - are sometimes disrupted in older adults. Evidence suggests that these disruptions may be worse in patients with AD and that AD patients may lose the ability to stay asleep or keep alert as the disease progresses. Sleep problems may also increase agitation among AD patients, according to the results of at least one study.
Another feature of AD is "sundowning," a term used to describe an increase in agitated behavior that occurs in the evening. This increased agitation may be explained by sleepiness or it may be that agitated behavior is more troublesome to caregivers after sun down. Whatever their causes, agitation and sleep problems result in severe stress for caregivers and are among the top reasons AD patients are given care in nursing homes instead of at home.
AD may also be