You may have heard that adults need 7-9 hours of sleep each night. But sleep quality also plays an important role and deep sleep is important for your physical and mental health.
When you rest, your body goes through different sleep cycle stages. For example, one of the stages includes deep sleep – the stage of sleep you need to wake up refreshed in the morning. Unlike rapid eye movement (REM) sleep, deep sleep slows your body and brain waves. It can be challenging to wake up from deep sleep, and you may feel particularly light-headed when you wake up.
Read on to learn more about this part of your sleep cycle.
What are sleep stages?
When you fall asleep, your body goes through three stages: non-REM sleep (NREM sleep) and REM sleep (REM sleep). It usually takes 90-120 minutes to go through all four steps, after which the cycle begins again. Adults typically do 4-6 such cycles per night. During the night’s first half, you spend more time in non-REM sleep. However, as the night progresses, more time is spent in REM sleep.
This brief drowsy phase marks the transition to sleep when breathing and heart rate slows down.
Breathing and heart rate slow down even more during this light sleep stage. Your muscles will relax, and your body temperature will drop. Stage 2 sleep lasts longer with each cycle throughout the night. About half of your sleep time is spent in this phase each night.
Previously divided into stages 3 and 4, stage 3 slow-wave sleep represents the deepest part of the sleep cycle, with the slowest brainwave frequencies and the highest amplitudes.
As the name suggests, the eyes move rapidly under the eyelids during REM sleep. Their brain activity is similar to that of an awake person. However, the muscles lack tension and are not moving. Most dreams, according to experts, happen during REM sleep.
What is deep sleep?
Deep sleep, also called slow-wave sleep, occurs in the third non-rapid eye movement (NREM) sleep stage. During deep sleep, electrical activity in the brain manifests as long and slow waves called delta waves. These waves must cover at least 6 seconds of a 30-second window to count that window as deep sleep. You usually fall asleep within an hour of falling asleep, and the duration of deep sleep gradually decreases as the night progresses. During this stage, automatic bodily functions such as breathing and heart rate also become very slow, and muscles relax. It can be difficult for someone to wake you up, and waking up from a deep sleep can leave you in a mentally dazed state for up to an hour.
Why is it important?
All stages of sleep are necessary for good health, but deep sleep has particular physical and mental benefits. During this, the body releases growth hormones, which work to build and repair muscle, bone, tissue, and immune system function. In addition, slow-wave rest may be necessary for regulating glucose metabolism. Competitive athletes appreciate deep sleep because it helps replenish their energy stores.
It is essential for cognitive function and memory, as well as for motor skills, language learning, and brain development.
How much deep sleep do you need?
To calculate how much deep sleep you need, determine how many hours of sleep you need. The average adult should get 7-9 hours of sleep per night. They should spend 13% to 23% of this time in deep sleep. If you sleep 7 hours a night, you’ll be in a deep sleep for about 55-97 minutes each night. To some extent, your body self-regulates how much deep sleep you get. You can also sleep more deeply when sleep disorders such as obstructive sleep apnea are treated. In contrast, frequent sleepers may get less deep sleep on subsequent naps because some deep sleep needs have already been met.
People tend to sleep less as they get older. They usually get more Stage 2 sleep instead.
Sleep disorders associated with deep sleep
Sleep disorders primarily associated with deep sleep are known as wakefulness disorders, including sleepwalking, sleep anxiety, and disturbed awakening. Adults can also experience these disorders, but they are more common in children and adolescents.
The episodes of these disturbances are usually brief and not remembered by the sleeper. However, events may affect wake-up times. Some sleepers with arousal disturbances experience excessive daytime sleepiness. Others may accidentally injure themselves or others during an awakening episode.
Sleep deprivation has also been linked to the following conditions:
1. Heart disease
2. Alzheimer’s disease
Signs that you are not getting enough deep sleep
1. Feeling drowsy
2. Reduced alertness and attention
3. Trouble learning and forming new memories
4. Cravings for high-calorie food
Tips for Getting More Deep Sleep
Getting enough sleep can help you get the deep sleep you require. You can develop a healthy sleep routine for your body by establishing consistent sleep and wake times. Good sleep hygiene can also help you get more sleep overall. Healthy sleep habits include:
1. Exercising regularly
2. Reducing caffeine intake in the afternoon and evening
3. Ensuring you have a quiet, cool, and dark sleep environment
4. Creating a relaxing routine to wind down in the evening
5. Taking a warm bath at the end of the day.
6. Improving your diet
7. Listening to binaural beats. These beats are created by listening to two slightly different tones, one in each ear. The difference in frequency of these tones creates a perceived third tone or binaural beat. Limited research suggests that these may help induce waves in the brain and thus stage 3 sleep.
A message from the Heartscope Specialist Group
To achieve restful sleep, it’s important to prioritise adequate sleep and maintain a balance across all sleep stages. If you experience daily sleep-related problems impacting your mood, cognitive performance, overall functioning, or physical health, it’s advisable to speak with your doctor. Keeping a sleep diary that documents your sleep habits and experiences can be helpful, and it’s beneficial to share this information with your doctor. If you have specific sleep-related conditions you would like to discuss, you can consider scheduling an appointment with a sleep physician at the Heartscope Specialist Group, which also offers online appointments for convenience.