How much deep sleep does an adult need?
A good night’s sleep and enough deep sleep are important. But how much do you need? And what exactly is deep sleep?
Sufficient deep sleep is necessary for everyone to be able to perform well during the day. The duration of this deep sleep and how much is necessary to feel fit vary from one person to the next. We have more to say about this later in the article. First a bit more explanation.
What is deep sleep?
Deep sleep is also called delta sleep or slow-wave sleep. During this phase, large waves with a delta pattern occur in your brain. These slow brain waves help to relax your muscles and slow down your breathing. This optimises your physical recovery and builds up energy for the next day.
You sleep in the following five phases: after a drowsy phase of 5 minutes on average, there is a light sleep phase of approximately 30 minutes. After the transition phase in which your muscles become more relaxed, you gradually go into deep sleep.
What exactly happens during deep sleep?
- The pituitary gland secretes human growth hormone.
- The body tissues recover.
- There is more blood flow to the muscles.
- The body’s energy levels are restored.
- The blood pressure drops.
If you are awakened in this stage and thus do not get enough deep sleep, you will feel confused, tired and sluggish. After these four phases in non-REM sleep, you enter REM sleep, also called dream sleep.
Percentage of deep sleep
The five phases of the sleep cycle are repeated four to five times in each sleep period. After each REM sleep period, you may wake up briefly, and usually you fall asleep again. During the final stage of NREM sleep, your EEG shows slow delta waves (measured brain waves). This stage is therefore also called slow-wave sleep (SWS). The deep sleep stage is where your body recovers, and it lasts the longest at the start of the night. It gets shorter with each repetition of the sleep cycle.
In adults, deep sleep represents 25 percent of sleep time on average. This percentage is an important part of your sleep pattern. This is because your brain fluid is also moving during this phase, allowing waste products to be carried away.
Reduced number of hours
The number of hours of deep sleep declines after you turn forty. It is estimated to drop by 2 percent every 10 years between the ages of 20 and 60. Once you are 70 years old, you may not even have any deep sleep. Older persons therefore sleep less effectively and for shorter times. Women aged 70 or older can still achieve 15 percent, but for men it can be as little as 5 percent.
By contrast, a newborn baby sleeps about two-thirds of the day. Your sleep cycle is also influenced by your biological clock. Some people naturally go to bed later, while others like to go to bed early.
Improving deep sleep
Good sleep and deep sleep are important, considering that on average we spend a third of our life asleep. An adult needs an average of 7 to 8 hours of sleep, although how many hours of sleep you need varies from one person to the next.
Sleep is necessary to give your brain a chance to process experiences and to let your body recover. If you don’t get enough deep sleep, you won’t feel well rested, so you should try to promote and prolong your deep sleep.
How can you improve your deep sleep?
- One way to contribute to good deep sleep is to not eat too much and to not drink any alcohol in the hours before you go to bed.
- A properly dim environment is also important, because the production of melatonin, the hormone that makes you sleepy, is blocked by light.
- To give your body a chance to fully relax and improve your deep sleep, a good bed with a proper mattress and a slatted base is essential.