How much deep sleep should I get each night?

There is no single required amount of deep sleep for every adult. Deep sleep often accounts for roughly 10% to 25% of total sleep, but the amount varies with age, activity, health and recent sleep loss. Younger people generally receive more deep sleep than older adults. A person sleeping eight hours might spend approximately one to two hours in deep sleep, but nightly variation is normal. Consumer watches and sleep trackers can only estimate deep sleep and may misclassify stages. It is usually more useful to focus on sufficient total sleep and how you feel during the day. Persistent fatigue, loud snoring or repeated waking deserves attention, even if a device reports a seemingly normal deep-sleep percentage.