For decades, sleep disturbance was a punch line: the cartoon dad snoring, the disgruntled partner burying their head under a pillow. But science is beginning to paint a less jovial picture. Sleep apnea—a relatively common disorder where breathing repeatedly stops and starts during sleep—is now being taken seriously as a potential biomarker for a host of major health conditions, from cardiovascular disease to Alzheimer’s, even anxiety and depression.

“Sleep is just as important for health as diet and exercise,” says Marishka Brown, director of the US National Center on Sleep Disorders Research. “Poor sleep affects both your mental and physical health; it contributes to cardiovascular disease,