While good nutrition and exercise are strongly associated with physical and mental wellbeing, we often neglect the importance of good sleep. Our body requires quality deep sleep in order to feel refreshed in the morning.
Read on to learn more about deep sleep and how you can improve this stage of your sleep cycle.
How much deep sleep do you need?
It is recommended that adults get seven to nine hours of sleep at night. Although restorative functions occur in all stages of the sleep cycle, deep sleep and REM sleep are the most important for restorative sleep.
Restorative sleep is vital for better body and mind health. It helps improve learning, decision making, productivity and memory. It also helps to increase creativity, energy, alertness and productivity.
Of the seven to nine hours, average sleep cycles show that 20 to 25 % of it is REM sleep. While there is no official consensus on how much REM sleep one should get, this seems to be a healthy amount of deep sleep.
Deep sleep should take up 10 to 25%, or 1 to 2 hours of an average 8 hour sleep duration at night.
As for light sleep, there is no minimum amount that you should get. In any case, it is almost impossible to avoid light sleep as it is the default stage when you nod off.
Basic anatomy of sleep
Let us start by understanding the basic anatomy of sleep. Our brain plays a large role when it comes to the sleep-wake cycle.
The hypothalamus, located deep inside the brain is a peanut sized structure that is the control center for sleep and arousal.
In the hypothalamus is a cluster of thousands of cells referred to as the suprachiasmatic nucleus (SCN). The SCN’s role in sleep is to receive information on light exposure from our eyes to help control our circadian rhythms.
Our brain stem, which is located at the base of the brain includes the medulla, midbrain and pons. It communicates with the hypothalamus on sleep-wake cycles. The brain stem is also important in regulating REM sleep as it signals muscles to relax during this stage of the sleep cycles to ensure that we do not act out our dreams.
Other parts of the brain, such as the thalamus and amygdala are also essential during REM sleep. The thalamus sends information such as images and sounds that make up our dreams to the cerebral cortex while the amygdala helps to process emotions.
The pineal gland, which is located within the two hemispheres of the brain also receives signals from the SCN. When the light goes down, the pineal gland produces the hormone called melatonin. Melatonin helps to establish our circadian rhythm and encourages sleep.
Stages of sleep
There are a total of 5 stages in the sleep cycle.
Stage 1 of sleep occurs when you move from being awake to being asleep. It is a light, non-REM sleep. During this stage, your body starts to relax. Your heartbeat, respiration, eye movements and brain waves start to slow down. Stage 1 lasts just for a few minutes.
Stage 2 of the sleep cycle is still a part of light sleep, but you are sleeping a little steadier at this stage. Your body continues to relax, and your core temperature drops. Your eye movements stop and your brain waves are slow although there may still be small bursts of activity in this stage. Stage 2 sleep should account for about 45 to 55% of the sleep cycle.
Stage 3 and 4
Stage 3 and 4 is when you get deep sleep, which is also known as ‘slow wave sleep’ or ‘delta sleep’. During these stages, your muscles are extremely relaxed, while your heartbeat, breathing and brain waves are at their slowest. You are most difficult to waken during this time in your sleep cycle.
Tissues growth and repair, as well as cellular energy is restored during Stage 4 sleep.
Deep sleep is longer during the first half of the night, becoming shorter and shorter in the following sleep cycles.
You move from non REM sleep to REM sleep about 90 minutes from when you first fell asleep. During REM sleep, your eyes move rapidly from side to side. Your heart rate, breathing and brain activity increases to near waking levels.
Because you are most likely to dream during this stage, your arms and legs become temporarily paralyzed during the REM stage to ensure that you do not physically act out your dreams while you sleep.
Benefits of deep sleep
The deep sleep stages are very important in the sleep cycle as it offers numerous health benefits.
1. Boosts learning and memory consolidation
Deep sleep promotes glucose metabolism which helps with both short term and long term memory as well as overall learning.
2. Growth and cell regeneration
Our pituitary gland releases growth hormones during the deep sleep stage. This is also the time when our bodies repair muscles and tissues, thereby relaxing them.
An increased flow of Cerebrospinal fluid (CSF) into our bodies also occurs during deep sleep. CSF clears beta-amyloid, a protein linked to Alzheimer’s disease, from our brain.
There is also an increased blood supply to muscles during deep sleep, which helps to strengthen and repair our muscles.
3. Strengthens the immune system
Deep sleep strengthens our immune system, helping us to fight infections, inflammation and illnesses.
4. Energy restoration
Deep sleep helps us to conserve energy and allows us to wake up feeling fresh and restored. This may be due to an increase in adenosine triphosphate in cells during deep sleep.
What happens when you don’t get enough deep sleep?
Poor sleep quality can have a negative effect on your physical as well as mental wellbeing.
Consider the following consequences of too little deep sleep or long term chronic insomnia:
- Alzheimer’s disease
- Memory loss, Dementia
- Heart disease
- Type 2 Diabetes
- High blood pressure
- Impaired growth in children
- Immune system dysfunction
- Risk of routine infections such as the common cold
Visible symptoms when not getting deep sleep
While the cumulative health and mental toll may take time to show, you may not be getting enough deep sleep if you have the following noticeable symptoms:
- Excessive sleepiness
- Frequent yawning
- Daytime fatigue or reduced productivity
- Easily irritable
- Red eyes/eye bags/dark circles around the eyes
- Needing caffeine
- Unable to focus
What causes lack of deep sleep?
It’s important to find out why you’re waking up feeling tired and being fatigued throughout the day. Here are some reasons for lack of deep sleep:
Stress and anxiety
Sleeping issues are frequently connected to stress and anxiety.
Ruminative thoughts, excess worry and fear can make it hard for one to fall asleep or stay asleep through the night. Lack of deep sleep due to stressful lives and worries can in turn, worsen anxiety, causing a negative cycle of anxiety disorders and sleeplessness.
The Covid-19 pandemic has also exacerbated anxiety issues, leading to many people experiencing sleep problems. Lockdowns, job losses, isolation and dealing with sickness during this uncertain time has caused many to lose sleep.
Anxiety is frequently connected to sleeping problems. Excess worry and fear make it harder to fall asleep and stay asleep through the night. Sleep deprivation can worsen anxiety, spurring a negative cycle involving insomnia and anxiety disorders.
Circadian rhythm disorders
Our natural sleep rhythm is usually driven by our internal ‘clock’ which encourages us to sleep at night. Circadian rhythm disorders occur when there are abnormalities or disruptions to this ‘clock’.
Jet lag, shift work, delayed sleep phase syndrome and advanced sleep phase syndrome can all cause circadian rhythm disorders.
Delayed sleep phase syndrome occurs when you fall asleep and wake up too late, while advanced sleep phase syndrome refers to when you fall asleep and wake up too early.
People who have insomnia may have issues falling asleep and staying asleep. They may wake up frequently during the night, causing interruptions to deep sleep. Insomnia can be caused by anxiety, depression, stress, jet lag and poor sleeping habits.
There is also a link between insomnia and Covid-19.
Snoring occurs when the air you inhale rattles over the relaxed tissues of your throat, producing noise.
While many adults who snore have no issues with sleep, snoring can be a problem because of the noise that it causes. It may even cause sleepless nights for your partner if he or she is a light sleeper. Snoring can also be a symptom of sleep apnea.
Sleep apnea is a condition in which the upper airway becomes partially or completely blocked when one is sleeping.
This causes breathing interruptions which cause the person to wake up. It certainly can be a disturbance to deep sleep and cause daytime sleepiness. Sleep apnea has been linked to high blood pressure, stroke and heart attack.
Restless legs syndrome
In restless legs syndrome, people move their legs with rhythmic or cyclic movements when they are asleep. This can cause brief awakenings during sleep, thus, interrupt deep sleep.
Older people may have trouble with deep sleep. Sleep apnea is not unusual for those who are older.
Your lifestyle can also be a factor affecting your sleep. Caffeine and alcohol intake can make it hard to fall and stay asleep.
Illness and medication
People with heart or lung issues may find it difficult to sleep because they are not able to breathe properly when they lie down. Certain drugs can also make it difficult to sleep.
Sleep study tests
If you’re having sleep issues, your doctor may recommend polysomnography, which is a comprehensive sleep test used to diagnose sleep disorders.
This test records several aspects of your sleep, including brain waves, heart rate, breathing, blood oxygen levels, and eye and leg movements.
Because you will be required to sleep during this test, it is usually carried out at night at a hospital or a sleep clinic. Once you are diagnosed with a sleep disorder, polysomnography can be used to adjust your treatment plan so that it is most effective.
Sleep studies can also be carried out at home. For example, home sleep apnea tests that employ a limited number of sensors can be used to diagnose obstructive sleep apnea. It is best however, to visit your physician if you suspect a sleep disorder.
How to improve deep sleep (tips)?
Here are some tips to help you get more deep sleep:
1. Have a consistent sleep schedule
A consistent bedtime and wake time is one of the best ways that enable you to get more deep sleep per night. Establish a sleep schedule around your average bedtime.
2. Increase total sleep
Your body needs to pass stage 1 and 2 of the sleep cycle before reaching deep sleep. If you are getting less than 6 hours of sleep each night, Increasing your total sleep time to 7 to 9 hours will help you to get more deep sleep
3. Have a relaxing bedtime routine
Take a warm shower, some light reading or meditating before bed can help you to sleep better. Ensure that your sleep environment is dark and relaxed. Electronic devices should not be used an hour before bedtime as the blue light that they eliminate can disrupt sleep.
4. Be careful with caffeine
Most people probably know that caffeine can have a negative effect on sleep. However, do you know that caffeine can stay in our system for up to 6 hours after consumption?
Caffeine can cause you to spend more time in Stage 1 and 2 sleep and decrease the hours you spend in deep sleep. To give yourself better chances of a solid sleep, take note of the time that you need to stop caffeine intake.
5. Sleep supplements
Sleep supplements can help you to relax, fall asleep easier and have better slow wave and REM sleep. Rilax is a natural, safe and effective sleep supplement that can help you get the restorative deep sleep that your body needs.
Natural ingredients in Rilax include Alpha S1-Casein Tryptic Hydrolysate (Lactium) and L-Theanine (Suntheanine). Extracted from the milk of Holstein cows in France, Lactium is a bioactive peptide that promotes slow delta brain waves and improves sleep quality.
Suntheanine is a natural amino acid that can be found in green tea leaves. It is a natural sleeping aid that increases alpha brain waves, thus, reduces anxiety, improves sleep quality and enhances general wellbeing. Both these ingredients are recognized as safe by the FDA.
6. Pink noise
Pink noise is random low frequency noises that can help improve deep sleep and even lead to better memory retention. A fan or an air purifier for their background noise as well as temperature control and purified air. There are also sound machines that feature pink noise that help you sleep.
Studies have shown that regular exercise helps with sleep quality. 20 to 30 minutes of exercise a day can help reduce stress and help you to feel good. Do keep in mind not to do strenuous exercise too close to bedtime as this can energize you and encroach on your bedtime routine.
Certain forms of Yoga as well as meditation are also known to improve overall sleep quality in people.
If you are really having trouble falling asleep or staying asleep, audio recordings with hypnotic suggestions promoting sleep may help your sleep quality. Ensure that you turn it off just before you drift off to set a timer to do the job. You don’t want the sounds to disrupt your sleep once you’ve nodded off.
Slow wave sleep, or deep sleep, is important for our bodies. Lack of it can result in grave health consequences.
As such, it is recommended that you have enough rest each night. Do get professional help if you find that you are still fatigued and tired all the time even after doing all that you can to improve your sleep quality.