Age-related decline in the brain's circadian clock may be why some older people have difficulty sleeping and adjusting to time changes, U.S. researchers say.
Researchers at UCLA say their study of the brain's master circadian clock -- known as the suprachiasmatic nucleus -- shows a key pattern of rhythmic neural activity begins to decline by middle age.
The SCN is the central circadian clock in humans and other mammals and controls the timing of the sleep-wake cycle and many other rhythmic and non-rhythmic processes in the body, a UCLA release said Monday.
"Aging has a profound effect on circadian timing," said Gene Block, a professor of psychiatry and biobehavioral sciences. "It is very clear that animals' circadian systems begin to deteriorate as they age, and humans have enormous problems with the quality of their sleep as they age, difficulty adjusting to time-zone changes and difficulty performing shift-work, as well as less alertness when awake.
"There is a real change in the sleep-wake cycle."
Large numbers of people over the age of 65 regularly take sleeping pills, but the effects of taking such pills over many years is not known, researcher Christopher Colwell said, adding the new research could lead to other options for getting a good night's sleep.