how much deep sleep per night

Adults typically need between 10% and 25% of their total sleep time to be deep sleep, which usually translates to about 40 to 110 minutes (roughly 1.5 to 2 hours) of deep sleep per night if they are sleeping the recommended 7 to 9 hours. Most sources recommend aiming for about 1.5 to 2 hours of deep sleep to support physical recovery, immune health, and brain function. This amount can vary by individual factors such as age, health, and activity level, with older adults generally requiring less deep sleep and children needing more.