A national poll conducted by the University of Michigan and released in October found that almost half of those 65 and older have trouble getting to sleep, and more than a third are taking prescription or over-the-counter sleep aids.

Older adults also have problems staying asleep, said Adam Spira, a sleep researcher at the Johns Hopkins Bloomberg School of Public Health. “Good sleep protects against negative outcomes, and those who sleep poorly are at higher risk of functional decline and depression,” he added.

The American College of Physicians (ACP) defines chronic insomnia as the presence of symptoms of distress and impairment that last for at least three nights a week for at least three months and are not linked to medical or mental problems or other sleep disorders, such as obstructive sleep apnea and restless legs syndrome.