Getting enough quality sleep is extremely important for your health and well-being. One of the most critical components of restorative sleep is the time you spend in deep, or slow wave, sleep. During this stage, your body and mind undergo important restorative functions that help you wake up feeling refreshed and energized. So how much deep sleep should you aim for each night? Here’s a comprehensive look at the science behind deep sleep and recommendations for how much you need at different life stages.
What is deep sleep?
Deep sleep is the most restorative stage of sleep. It occurs during slow wave sleep, which is the third stage of non-REM sleep. Your brain waves become even slower during deep sleep, with an increase in delta brain waves. It’s much more difficult to wake someone up when they are in deep sleep compared to lighter stages.
During deep sleep, a variety of restorative functions occur:
- Tissue growth and muscle repair. Deep sleep stimulates the production of human growth hormone, which facilitates muscle and tissue repair and growth.
- Boosted immune function. Your body produces infection-fighting antibodies and cytokines during deep sleep.
- Memory consolidation. Your mind consolidates memories and new information from the day.
- Brain detox. Cerebrospinal fluid flows more freely to wash away waste products like beta amyloids that build up in the brain.
Getting sufficient deep sleep allows you to wake up feeling mentally sharp and physically rejuvenated.
How much deep sleep do adults need?
Experts recommend that adults get at least 15-20% of their nightly sleep in the deep sleep stage. On a typical 8 hour sleep schedule, that equates to:
- 1.2 – 1.6 hours of deep sleep per night
However, the amount of deep sleep needed can vary significantly based on your age, activity levels, and health status:
Younger adults need more deep sleep
Younger adults tend to get about 20% of their sleep in the deep stage. As you age, the time spent in deep sleep naturally decreases. Teenagers may spend closer to 25% in deep sleep to support growth and development.
Athletes need more deep sleep
People who are very physically active, like athletes, may need more deep sleep to promote muscle recovery after intense workouts. Athletes may spend 22-24% of their sleep in deep stages.
Chronic health conditions reduce deep sleep
Many health conditions like insomnia, sleep apnea, diabetes, and depression can reduce the amount of deep sleep you get each night. Prioritizing treatment for medical issues can help improve sleep quality.
Pregnancy alters sleep architecture
Hormonal changes shift the proportion of sleep stages during pregnancy. Deep sleep decreases, especially in the third trimester. Expectant mothers still require adequate deep sleep and may need to sleep longer or nap to obtain it.
How can you get more deep sleep?
If you feel like you’re not getting enough deep, restorative sleep, there are several natural remedies to try to get more high-quality slumber:
- Optimize sleep hygiene. Follow practices like limiting blue light exposure in the evening, avoiding caffeine in the afternoon, and keeping your bedroom cool and dark.
- Reduce stress through yoga, meditation, or relaxing activities before bed.
- Avoid alcohol, which reduces deep sleep later in the night.
- Exercise during the day to promote deeper sleep at night.
- Consider magnesium or melatonin supplements, which may help induce deeper sleep.
You may also want to experiment with biphasic or polyphasic sleep schedules, which involve taking multiple short naps throughout the day. This can allow you to get more deep sleep by aligning nap times with deep sleep cycles.
Signs you’re not getting enough deep sleep
Here are some signs that you may not be spending enough time in the critical deep sleep stage:
- Excessive fatigue and sleepiness during the day
- Frequent illnesses or infections
- Trouble concentrating, learning new information, or memorizing things
- Waking up feeling stiff or sore
- Mood changes like irritability or anxiety
- Slower reaction times or reduced athletic performance
Pay attention to these signs from your mind and body. If you regularly feel this way even after 7-9 hours of sleep, then you may need more deep restorative slumber.
How is deep sleep measured?
There are a few different ways researchers and sleep specialists measure deep sleep:
Polysomnography (PSG)
The gold standard for sleep studies is a polysomnogram, usually performed in a sleep lab. This test monitors brain waves, heart rate, oxygen levels, eye movements, and muscle contractions to precisely determine each stage of sleep.
Home sleep apnea tests
Basic home sleep apnea tests monitor heart rate, blood oxygen, breathing, and movement. They can estimate total sleep time and time spent in deep vs. light sleep.
Sleep tracking devices
Wearable devices and sleep tracking phone apps estimate sleep stages based on movement and heart rate patterns. Their accuracy for measuring deep sleep varies.
Sleep journals
Keeping a sleep diary to track factors like sleep quality, energy, and alertness can provide insight into whether you’re getting enough deep, restorative sleep.
| Measurement Method | Pros | Cons |
|---|---|---|
| Polysomnography | Most accurate and detailed sleep data | Expensive, requires sleep lab |
| Home sleep tests | Convenient, monitors sleep cycles | Less accurate than lab PSG |
| Sleep tracking devices | Affordable, easy home use | Varying accuracy for sleep stages |
| Sleep journals | Free, tracks sleep quality | No objective sleep stage data |
Deep sleep changes across the lifespan
Deep sleep patterns change significantly across the lifespan, from infancy through older adulthood:
Newborns (0-2 months)
Newborns spend about 50% of their 12-18 hours of daily sleep in active (REM) sleep and only about 25% in quiet (NREM) deep sleep. Their sleep cycles are about 50 minutes long.
Infants (3-11 months)
Infants’ total sleep drops to about 14 hours per day. Deep sleep increases to 50% of nighttime sleep, usually in longer blocks of 2-3 hours. Daytime naps contain mostly active REM sleep.
Toddlers (1-3 years)
Toddlers sleep 11-14 hours, with the amount of deep sleep similar to infants. However, naps start to contain more deep sleep as toddlers transition to one daytime nap.
Preschoolers (3-5 years)
Preschoolers sleep about 10-13 hours total with deep sleep comprising about 40% of nighttime sleep. Their nap durations shorten with more deep sleep.
School age (6-13 years)
School age children sleep 9-12 hours, with deep sleep making up 25-30% of nighttime. Their sleep architecture resembles adult patterns but with longer deep sleep cycles.
Teenagers (14-17 years)
Teenagers require 8-10 hours of sleep, but tend to get less due to later bedtimes. Teens have the highest percentage of deep sleep, around 20-25% each night.
Young adults (18-25 years)
Young adults have the same deep sleep requirements as teenagers – about 20% of total sleep. But sleep duration decreases to an average of 7-9 hours per night.
Adults (26-64 years)
Adults spend about 15-20% of their nightly sleep in the deep sleep stage. Total sleep ranges from 7-9 hours for most healthy adults.
Older adults (65+ years)
Time in deep sleep decreases to 10-15% for adults over 65. Growing difficulty falling and staying asleep also reduces total nightly sleep to 6-8 hours typically.
Deep sleep recommendations by age
Here’s a quick reference guide for deep sleep recommendations across age groups based on percentage of total sleep time:
| Age | Deep Sleep % |
|---|---|
| Newborns | 25% |
| Infants | 50% |
| Toddlers | 40% |
| Preschoolers | 40% |
| School age | 25-30% |
| Teenagers | 20-25% |
| Young adults | 20% |
| Adults | 15-20% |
| Older adults | 10-15% |
Conclusion
Deep sleep is vital for restoring the mind and body. Adults should aim for at least 15-20% of their sleep to occur in the deep stage, which allows for tissue repair, immune function, brain detoxification, and memory consolidation. However, deep sleep needs change across the lifespan, with infants and teenagers requiring a higher percentage of deep sleep than older adults. If you feel like you’re not getting enough refreshing deep rest based on symptoms like fatigue or illness, try improving your sleep hygiene and speak with your doctor about underlying issues impacting your sleep. Consistently obtaining your recommended amount of deep sleep ensures you can wake up feeling mentally sharp and energetic every day.