Much like a clock on the wall, our cells have their own 24-hour timeline. When they’re in sync, our body clock may act as a protective barrier against mental and physical illnesses.

But throw in some jet lag, a night shift or a bout of insomnia, and suddenly the clock’s hands are spinning out of control — potentially leaving us more vulnerable to viral infections and depression, scientists say.

Richard Friedman, a professor of clinical psychiatry at Weill Cornell Medical College, recently recalled a U.S. patient who suffered from manic depression. The man became depressed after returning from a trip to Europe, but seemed to snap out of it after a fun trip out West.

His post-Europe mood changes, it turned out, weren’t caused by the back-to-reality blues. “The problem turned out to be a disruption in his circadian rhythm,” Friedman wrote in an op-ed in the New York Times Sunday Review.

“He didn’t need drugs; he needed the right doses of sleep and sunlight at the right time,” the psychiatrist wrote. “It turns out that that prescription could treat much of what ails us.”

That’s not to say restoring your internally driven cycles will rid you of depression or make you immune to the flu. But a growing number of studies in recent years indicate that maintaining our internal rhythm is important for our overall health.

Our circadian rhythm represents the biochemical and physiological processes that rise and fall over the course of 24 hours, including those related to hormones, body temperatures and eating and digesting food.

Friedman pointed to a 2001 study that illustrated the link between sleep, sunlight and mood. In Milan, a team of psychiatrists noticed that hospitalized bipolar patients who stayed in rooms with views of the east were discharged earlier than patients with westward-facing rooms.

– Maria Gallucci

Read more: How weird sleep schedules disrupt our body clocks

Image by Gregory Pappas from Unsplash