She d.ied in his sleep from doing this: I implore you, don’t do it. It causes heart attacks and strokes.

1. Sleeping on Your Back with Untreated Sleep Apnea

One of the most concerning issues is untreated obstructive sleep apnea—a condition where breathing repeatedly stops and starts during sleep.

Typical signs include loud snoring, gasping during the night, or waking up feeling unrefreshed. When breathing pauses occur, oxygen levels drop, triggering spikes in heart rate and blood pressure. Over time, this repeated stress may increase cardiovascular risk.

Sleeping on your back can make symptoms worse, as gravity can narrow the airway.