You cannot switch deep sleep on at will, but you can make it more likely. The habits that help most are ordinary ones: a consistent sleep schedule, enough total sleep, daytime activity, a cool and dark bedroom, and going easy on alcohol and late caffeine. Before chasing a number on a sleep tracker, it helps to understand what deep sleep is and why the figures you see are only estimates.
What deep sleep is
Sleep is not one uniform state. Through the night the brain moves through cycles of lighter sleep, deep sleep and REM sleep, the stage most associated with vivid dreaming. Deep sleep, also called slow-wave sleep, is the stage in which brain waves are slowest and it is hardest to wake someone up. It tends to be concentrated in the first part of the night, while REM sleep becomes longer towards the morning.
Deep sleep is thought to play a part in physical recovery, immune function and the processing of memories. People woken from it often feel groggy and disoriented for a short while, which is one sign of how deep this stage is.
How much deep sleep do you need?
There is no single target that suits everyone. Deep sleep makes up a portion of each night, and that portion naturally shrinks with age, so an older adult will usually have less than a teenager. What matters more for most people is getting enough total sleep on a regular basis; public health guidance commonly suggests at least seven hours a night for adults. When total sleep is cut short, the body tends to prioritise deep sleep early on, but the night as a whole still suffers.
A better question than "Am I getting enough deep sleep?" is often "Do I wake up reasonably refreshed and get through the day without struggling to stay alert?"
A word about sleep trackers
Watches, rings and phone apps estimate sleep stages from movement, heart rate and sometimes breathing. They can be useful for spotting patterns, such as later bedtimes on certain days, but they are not as accurate as a sleep study in a clinic. Worrying about a low deep-sleep score can itself make sleep worse, so treat the numbers as rough guidance rather than a verdict.
Habits that may increase deep sleep
- Keep regular hours. Going to bed and getting up at similar times every day, weekends included, helps the body clock organise sleep stages.
- Be active during the day. Regular exercise is linked with better sleep quality. Very intense workouts close to bedtime can leave some people too alert, so earlier in the day may suit you better.
- Get daylight in the morning. Natural light soon after waking helps set the body clock for the evening.
- Watch the caffeine. Coffee, tea, energy drinks and some soft drinks can affect sleep for hours. Try keeping them to the morning.
- Go easy on alcohol. It may make you drowsy, but it tends to disrupt sleep later in the night and leave it lighter and more broken.
- Keep the bedroom cool. Body temperature naturally drops at night, and a room that is too warm can make sleep restless. Our article on why you get so hot when you sleep has practical ideas.
- Wind down. A quiet half hour before bed with low light and no work messages gives the mind time to settle.
- Avoid heavy meals late. A large meal right before bed can make it harder to sleep soundly.
Common things that cut into deep sleep
| Factor | Why it matters |
|---|---|
| Irregular schedule or shift work | Confuses the body clock, so sleep stages become less organised |
| Stress and racing thoughts | Keep the body on alert and make sleep lighter |
| Noise and light | Can cause brief awakenings you may not remember |
| Snoring or pauses in breathing | May fragment sleep repeatedly through the night |
| Pain or frequent trips to the toilet | Interrupt the cycles before deeper stages are reached |
If you wake repeatedly in the small hours, the guide on why you keep waking up at night goes through the most common reasons. Stress is a frequent culprit, and the suggestions in how to reduce stress at work may help if your job follows you to bed.
What does not help much
Lying in bed for longer in the hope of catching up often leads to more time awake. Long naps late in the afternoon can reduce sleep pressure at night. And supplements sold with deep-sleep claims vary widely in quality and evidence; speak to a pharmacist or doctor before trying them, especially if you take other medicines.
Signs it is worth seeing a doctor about sleep
See a doctor if you feel unrefreshed most mornings despite enough time in bed, if you are very sleepy during the day, or if a partner notices loud snoring, gasping or pauses in your breathing. These can point to sleep disorders such as sleep apnoea, which are treatable. Persistent insomnia, low mood or pain that disturbs sleep also deserve a proper assessment.
