Everyone knows getting a “good night’s sleep” matters. And while naming the stages of the sleep cycle may be difficult, the benefits of deep sleep are felt every morning.
The third stage of sleep, deep sleep, is linked to physical recovery, immune function and memory consolidation. The desire to feel refreshed in the morning may have you asking how much deep sleep is necessary, and how you can boost the time you spend in this state. A person’s ideal sleep amount depends on a host of factors, including age, sex, activity levels and health, says Michael Perlis, a professor and director of the Behavioral Sleep Medicine program at the University of Pennsylvania.
Here’s what to know.
How Much Deep Sleep Does a Person Need?
For a healthy adult, ages 18 to 65, deep sleep runs roughly 15 to 23 percent of the night − somewhere around an hour to 90 minutes across a full seven to nine hours of sleep, says Matthew Walker, a professor of neuroscience and biomedical engineering at The University of Texas at Dallas.
But experts agree there isn’t a one-size-fits-all number.
Still, listening to your body is important. Feeling groggy during the day, experiencing foggy memory and struggling to concentrate could be signs you’re not getting enough deep sleep, though these are signs of insufficient sleep in general and it can be hard to determine if the culprit is a lack of REM or deep sleep.
The real red flag, Walker says, is persistently waking unrefreshed, even after a full night in bed. Protecting your total sleep and your schedule helps deep sleep do its job better, he adds.
How Can You Increase Your Deep Sleep Hours?
There’s a few things you can do to increase deep sleep hours, starting with stopping destructive habits and creating better environments.
This includes keeping a more regular schedule – deep sleep is front-loaded during the first half of the night, Walker says, so “a consistent, early-enough bedtime protects it” – as well as keeping the bedroom cool. Since the brain needs to drop its core temperature by roughly a degree to descend into deep sleep, a bedroom temperature of around 65-67 degrees Fahrenheit will help.
Additionally, receiving daylight in the morning and moving regularly during the day can also pave a smoother path to deep sleep. What not to do right before bed? Working out, drinking alcohol and consuming caffeine, Walker says.
Other factors limiting deep sleep include a person’s age (beginning in the late 20s, deep sleep starts declining) as well as chronic stress and sleep apnea, a very common but underdiagnosed condition that can “shatter deep sleep hundreds of times a night without the sleeper ever knowing,” according to Walker.
