If you're like us and you're striving for a balanced and healthy lifestyle, then you should know that few factors are as critical as quality sleep.

Among the various stages of sleep, none is as important as deep sleep, which is a period of deep, restorative rest.

Adequate deep sleep serves repair and restoration functions that are essential for feeling your best every day. It also helps the brain and body prepare to take in new information and adapt to new environments.

But how much of this deep sleep do you really need to have optimal well-being in your daily life?

This question goes beyond casual curiosity and must be answered in an evidence-based manner based on what science defines.

In this article we will analyze the reasons why deep sleep is so important for a balanced lifestyle, how many hours of it we need to feel good, and ways to increase it.

What is deep sleep?

Deep sleep, also called slow-wave sleep, occurs in the third stage of non-rapid eye movement (NREM) sleep. During deep sleep, electrical activity in the brain occurs in long, slow waves called delta waves. These waves have a frequency of 0.5 to 2 Hertz and must constitute at least 6 seconds of a 30-second period for this period to be considered deep sleep.

Typically, you fall into a deep sleep within an hour of going to bed and as the night progresses. you experience progressively shorter periods of deep sleep . During deep sleep, body functions, such as breathing and heart rate, are also very slow, and your muscles relax. It now becomes difficult to wake up from a small noise or your alarm, but when you do, you feel disoriented, dizzy, and mentally foggy for the next hour.

Does it remind you of something? 🤗

What are the stages of sleep?

Once you fall asleep, your body cycles through four stages of sleep, the first three are non-rapid eye movement (also called non-REM or NREM), followed by rapid eye movement (REM) sleep.

It usually takes 90 to 120 minutes to go through all four stages, at the end of which the cycle begins again.

Adults typically go through four to six cycles per night, with the first half of the night spent in NREM sleep. However, as the night progresses, the time spent in REM sleep increases.

• Stage 1: This short, drowsy stage marks the transition to sleep, when your breathing and heart rate begin to slow down.
• Stage 2: In this stage of light sleep, your breathing and heart rate slow down even further. Your temperature drops and your muscles relax. Stage 2 sleep lasts longer in each cycle throughout the night. Abouthalf of your total sleep each night is spent in this stage.
• Stage 3: Stage 3 sleep represents the deepest sleep of the sleep cycle, when brain waves have the slowest frequency and greatest amplitude.
• REM: As the name suggests (Rapid Eye Movement), during REM sleep the eyes move rapidly under the eyelids and brain activity is similar to that of a person who is awake. However, your muscles usually do not move. Experts believe that most of our dreaming occurs during REM sleep.

Why is deep sleep important?

While all stages of sleep are essential for good health, deep sleep offers specific physical and mental benefits.

During deep sleep, our bodies release growth hormone, which works to build and repair muscle, bone, and tissue. Deep sleep also promotes immune system function and may be important for regulating glucose metabolism . Elite athletes value slow-wave sleep as it helps replenish their energy stores .

Deep sleep is also important for cognitive function and memory and is considered an important factor in language learning, motor skills, and brain development.

Throughout the day, we receive a lot of new information that strengthens the synapses, or communication points, in our brain networks. However, without rest and deep sleep, our brain cannot continuously absorb new information.

Researchers suggest that deep sleep plays a role in preparing synapses for the next day. In other words, our brain evaluates new information and experiences and then retains and consolidates only those that are most important to avoid saturating memory pathways.

Although this theory is still under investigation, evidence suggests that people gain a greater percentage of deep sleep after learning a new task and exhibit higher concentrations of slow waves in brain areas related to the task.

How much deep sleep do you need?

To calculate how much deep sleep you need, first determine how much sleep you need overall.

Most adults should aim for seven to eight hours of sleep each night, with experts believing that 13%-23% of that time should be spent in deep sleep. That's about 105-120 minutes a night.

To some extent, the body self-regulates deep sleep. For example, you may spend more time in deep sleep if you are recovering from a period of sleep deprivation. Conversely, people who sleep frequently may experience less deep sleep, as part of their deep sleep needs have already been met during the day.

As people age, they tend to have less deep sleep. Older people typically spend more time in stage 2.

Sleep disorders related to deep sleep

Sleep disorders specifically associated with deep sleep are called arousal disorders and include sleepwalking, bad dreams, and confusional arousals. While adults can experience these disorders, they are more common in children and adolescents.

Awakening here does not mean that the person or child wakes up. An "awakening" is a partial awakening, usually from deep sleep. Typically, the person transitions from deep sleep to a mixture of very light sleep and/or partial wakefulness. This stage change usually leads to a state of confusion called "awakening confusion."

Typically, episodes of these disorders are brief and the sleeper does not remember them. However, the events can affect the hours they are awake and need to be alert. Some people with wakefulness disorders experience excessive daytime sleepiness, while others may accidentally injure themselves or others during an episode.

Measurements of the brain waves of sleepwalkers have found that many individuals continue to experience a certain percentage of slow waves—which are characteristic of deep sleep—during a sleepwalking episode. Adult sleepwalkers also show fluctuations in slow wave activity throughout the rest of the night.

What happens when deep sleep is not enough?

In addition to causing fatigue, a lack of deep sleep can have various effects on your body.

Because deep sleep is part of the memory formation process, when there is not enough deep sleep the brain can have difficulty consolidating memories. Even after one night of inadequate sleep you may experience difficulty learning or remembering information.

On a physical level, insufficient deep sleep can reduce your immune response to vaccines and make you more vulnerable to infections. During deep sleep, potentially harmful waste products are eliminated from the brain, and therefore, its lack can lead to the development of neurological diseases, such as Alzheimer's and Parkinson's disease .

Additionally, sleep deprivation is associated with hormonal changes that drive our appetite for high-calorie foods. Lack of slow-wave sleep, in particular, is thought to contribute to insulin resistance and the development of type 2 diabetes and heart disease. Getting more sleep can reverse some of these effects .

Who can't sleep deeply?

Because deep sleep occurs in multiple segments during sleep, anyone who sleeps less than the recommended hours is likely not getting enough deep sleep. Fragmented sleep due to sleep disorders or sleeping at times that do not align with the natural sleep-wake cycle (e.g., when working shifts) can also reduce the percentage of slow-wave sleep.

Some people with insomnia experience changes in their sleep cycles, and as a result, they may have more stage 1 sleep and less deep sleep. Stress and aging can also reduce levels of deep sleep. Additionally, people with conditions such as schizophrenia and Alzheimer's disease experience less slow-wave sleep.

Recently, some researchers have observed that people with damaged hippocampus , or the brain's memory center, experience much less slow-wave sleep than people with an intact hippocampus.

Experts suggest that memory signals sent from the hippocampus are a necessary trigger for the generation of the slow delta waves seen in deep sleep. Therefore, problems with memory formation may be a cause, rather than a consequence, of a lack of deep sleep.

Here are some signs that indicate you are not getting enough sleep in the deep sleep stage:

• Feeling of uneasiness and drowsiness
• Reduced alertness and attention
• Difficulty learning and forming new memories
• Craving for high-calorie foods

Tips for more deep sleep

Getting the amount of sleep you need overall is a good start to helping you get enough deep sleep. By establishing a consistent bedtime and wake-up schedule, you can develop a healthy sleep schedule for your body. Practicing good sleep hygiene can also help you get more sleep overall. In summary, good sleep hygiene includes:

• Regular exercise
• Reducing caffeine intake (at least after noon)
• Ensuring a quiet, cool and dark sleeping environment
• Creating a relaxing nighttime routine before bed

There are a few additional steps you can try to increase deep sleep:

• Take a warm bath: Warming your body at least an hour before bed can help induce slow-wave sleep. The warmth from the bath draws heat to your hands and feet, which then dissipates. This process allows you to cool down to a comfortable temperature for sleep.
• Change your diet: What we eat and drink before bed affects how we sleep at night. One small study found that people who ate a diet high in saturated fat got less slow-wave sleep. People who ate more fiber were more likely to have deeper sleep.
• Use a gravity blanket: A gravity blanket applies a steady pressure to the body that helps the nervous system relax and the body enter a state of rest and restoration, which promotes deep sleep and reduced awakenings during the night.

If you want to learn more information about how to increase deep sleep , you can read the detailed article we have written.

Improve your sleep quality with a gravity blanket

Gravity blankets are the most effective way to deal with insomnia and stress without medication, as they have been used for many decades to help people suffering from anxiety disorders, autism, and other sensory disorders.

How do they work?

They are designed to apply gentle, steady pressure to the entire body, which occupational therapists call “ Deep Tactile Pressure .” This steady pressure relaxes the nervous system and helps the body naturally increase levels of serotonin and melatonin (the hormones of happiness and sleep) while reducing levels of cortisol, which is responsible for stress.

As a result, the mind stops "racing", the heart rate drops, the mood improves and the body enters a state of complete relaxation.

Choose the one that weighs closest to 10% of your body weight and upgrade your sleep from the very first night.