Researchers at the University of California, Berkeley, have found that the unmet sleep needs of the elderly elevate their risk of memory loss and a wide range of mental and physical disorders.

In an article published Wednesday in the journal Neuron, the researchers argue that unlike more cosmetic markers of aging, such as wrinkles and gray hair, sleep deterioration has been linked to such conditions as Alzheimer's disease, heart disease, obesity, diabetes and stroke.

"Nearly every disease killing us in later life has a causal link to lack of sleep," said the article's senior author, Matthew Walker, a UC Berkeley professor of psychology and neuroscience. "We've done a good job of extending life span, but a poor job of extending our health span. We now see sleep, and improving sleep, as a new pathway for helping remedy that."

Though older people are less likely than younger cohorts to notice and/or report mental fogginess and other symptoms of sleep deprivation, numerous brain studies reveal how poor sleep leaves them cognitively worse off.

Moreover, the shift from deep, consolidated sleep in youth to fitful, dissatisfying sleep can start as early as one's 30s, paving the way for sleep-related cognitive and physical ailments in middle age.

Walker and fellow researchers cite studies that show the aging brain has trouble generating the kind of slow brain waves that promote deep curative sleep, as well as the neurochemicals that help us switch stably from sleep to wakefulness.

"The parts of the brain deteriorating earliest are the same regions that give us deep sleep," said article lead author Bryce Mander, a postdoctoral researcher in Walker's Sleep and Neuroimaging Laboratory at UC Berkeley.