Our natural sleep and wake cycles are determined by our body’s circadian rhythm.

As board-certified sleep specialist Michael J. Breus, Ph.D., explains to mbg, the circadian rhythm is a roughly 24-hour cycle that your body repeats over and over. “It basically ‘runs’ your sleep—starting it and stopping it—by sending out neurochemical signals telling each area, organ, or receptor site what to produce, what to receive, and what to do,” he explains.

And according to naturopathic sleep doctor Catherine Darley, N.D., “There are also clock genes in each cell, which makes the cell do more or less of its function at different times of the day.”

Many of our rhythms are dictated by the suprachiasmatic nucleus (SCN), the body’s “central pacemaker” in the hypothalamus of the brain. Environmental factors like lighting entrain this pacemaker, which is why you’ll often hear the advice to seek bright light during the day and darkness at night to maintain a healthy circadian rhythm.

Keeping your body clock in sync with the actual clock and its steady cycles of day and night can pay dividends for many aspects of your health, including your sleep.