Deep sleep is the mentally and physically restorative stage of sleep. How much of it do you actually need?

Deep sleep refers to slow-wave sleep — a stage in the sleep cycle when brain waves slow down. Getting enough deep sleep is crucial for numerous bodily functions. But how to increase deep sleep isn’t ...

Deep sleep helps you feel refreshed and typically makes up 20–25% of total sleep time, or about one to two hours per night for adults. If you're not sleeping soundly, certain strategies can help ...