Narrator: This is Science Today. More than half of all older adults have trouble sleeping - a disturbance that impairs their day-to-day functioning. Dr. Michael Irwin, a professor of psychiatry at UCLA, led a study that found that practicing tai chi chih, a Westernized version of the ancient Chinese martial art tai chi, promotes healthier sleep in older adults.

Irwin: So, tai chi is very novel in that it brings together both an exercise component as well as a stress reduction component, all in one. And importantly, in comparison to exercise, tai chi is so easy to learn and its benefits can be achieved even among older adults who have physical limitations.

Narrator: Irwin says previous studies found that a single session of tai chi activates the sympathetic nervous system and lowers one's heart rate and blood pressure.

Irwin: ... which then carry forward to lead to improvements in sleep throughout the night.

Narrator: For Science Today, I'm Larissa Branin.