How to increase deep sleep and why you need it

By Vladimir Marchenko

1. What causes deep sleep
2. How much deep sleep is normal
3. Lack of deep sleep and its consequences
4. How to get more deep sleep

People who suffer from sleep disorders often wonder how to get deep sleep naturally. Today we will tell you why this stage of sleep is so important for a good rest and whether it can somehow be extended.

What causes deep sleep

Deep sleep is one of the final stages of slow-wave sleep (Non-REM, NREM). At this time, the brain generates delta waves (therefore, this stage is sometimes called delta-sleep), the body is almost completely relaxed and motionless, the muscles, including the ocular muscles, do not contract. As the activity of delta waves gradually increases, it becomes more difficult to wake a person up, and he hardly perceives any sounds or stimuli from the outside world. It is noteworthy that at this stage a person can also see dreams, although not as vividly and memorably as in the REM phase. They tend to be more realistic episodes or life memories.

During the deep sleep, muscles and skin are restored, immunity is strengthened, energy supplies are accumulated. At the level of the psyche, memory is reactivated, unnecessary information is removed and important information is stored in long-term memory. In other words, answering the question “what is deep sleep”, we can say that it is the stage when the renewal of the body resources occurs and that’s why it is considered the most useful and healthy stage of sleep.

How much deep sleep is normal

In September 2020, ScienceAdvances (advances.sciencemag.org/content/6/38/eaba0398) published a study held by American scientists led by the neuroscientists from the University of California. The study presents a mathematical model that reflects the evolution of certain brain functions in children from an early age to 15 years old. The calculations were based on parameters such as metabolic rate and brain volume, as well as the time spent in each phase of sleep.

Scientists have found that the main function of sleep changes dramatically from about 2.5 years old. At this time, once the main "frame" is created, "cleaning" of memory and daily recovery begins. It is during this period that the phase of REM sleep decreases in duration while deep sleep increases. This trend persists throughout a person's life.

Among adults, deep sleep takes up to 20-30% of the total sleep duration, gradually decreasing with age to 7%. Thus, the normal duration of deep sleep based on the 8-hours sleep norm is:

• For young people under 30 - 120 min;
• For people from 31 to 55 years old - 100 minutes;
• From 55 to 60 years old - 85 min;
• Over 60 years old - 75-80 min.

These indicators are average and may differ, depending on a specific person.

Lack of deep sleep and its consequences

The following signs indicate that the amount of deep sleep for a specific person needs to be extended:

• impairment of memory, coordination, attention;
• difficulties with learning new material;
• weight gain;
• signs of ageing, not appropriate for the real age;
• frequent colds and infectious diseases.

Lack of slow-wave sleep negatively affects physical endurance and mental performance. One cannot work effectively and has difficulties in accomplishing tasks that require coordination. One of the common side effects is sleep apnea syndrome (respiratory problems during sleep). Over the longer term, episodes of sleepwalking and other disorders may occur. Waking a person up during deep sleep is not advised as it can cause headaches during the day.

How to get more deep sleep

First, you need to know how much time you spend in slow-wave sleep. You can collect data from your smartwatches or fitness trackers. However they are often not very accurate, so it is better to use polysomnography. Usually, the appropriate specialist is engaged in this procedure who can draw up a list of recommendations based on the data obtained.

So, how to get deep sleep of increased duration? Use these simple recommendations:

1. Increase the total sleep duration and sleep quality, and it’s very likely that the duration of deep sleep will be prolonged as well. Therefore, pay attention to quality rest, lasting at least 8 hours (or another time indicator corresponding to your age).

2. Stick to a sleep schedule, go to bed and wake up at about the same time. This applies to both workdays and weekends, including holidays, during which it is more difficult to adhere to the established sleep schedule.

3. Do not drink alcohol or energy drinks before bedtime and quit smoking.  All these factors negatively affect the quality of sleep. Better to replace them with a hot tub with relaxing oils half an hour before going to bed.

4. Do not eat 3 hours before bedtime. Overeating, eating sweet, spicy, high-calorie foods negatively affect falling asleep and sleep duration.

5. Include the products with magnesium into the diet. It normalizes the functioning of the nervous system and has a positive effect on deep sleep. Beans, spinach, walnuts, almonds, dates, sesame seeds, and wheat bran contain a lot of magnesium.

6. Moderate physical activity 3-4 hours before bedtime or walking a couple of hours before falling asleep helps the body to rest and recover during the deep sleep phase.

7. Create a comfortable sleep environment. The room temperature should be at the level of 18-21 degrees Celsius (make sure to ventilate the room), you need to fall asleep with curtains and in silence. Before falling asleep, do not spend too much time with gadgets, because the “blue” light from them will not allow the brain to calm down.

8. Practice relaxation and meditation techniques. Before going to sleep it's important to create the right mood for bedtime. This can be also done using relaxation apps.

One of the latest developments in the area of healthy sleep is the Hypnopedia mobile app for iOS. It implements a set of features which, by interacting with sleep, improve users’ mental health and psychophysiological characteristics (productivity, motivation, etc.). For smooth falling asleep, there are playlists of natural relaxing sounds which turn off automatically at night. After, the sleep session can be continued by another unique feature - thematic affirmations, conveniently arranged by categories into playlists so that you can choose the ones that suit you best and “listen” to them while sleeping. Recorded affirmations are played at the most suitable for perception sleep time, do not disturb or wake you up, including in the stage of deep sleep. The information is perceived subconsciously and has a long-term positive effect on the further state of the user. Sleep session is completed by awakening at the desired time with the help of a smart alarm clock which ensures that your head will be light and fresh after the night. You can download app for free here:

We would like to note, however, that increasing the duration of slow-wave sleep above the level of the physiological maximum (about a third of the total duration of sleep for an adult) can also lead to negative consequences.

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Thus, deep sleep is an essential component of rest and recovery. Delta-sleep improves health and well-being and makes us look fresher and younger. To prolong the duration of it, you need to adjust the wakefulness-sleep cycle, break bad habits and replace them with new healthy ones. In the end, it may be not as hard as you thought, to achieve deep sleep.