Medically reviewed by Tanja Premru-Sršen Deep sleep, also called slow-wave sleep, describes the NREM third stage of sleep. At this stage, our heartbeat and breathing are at their lowest, our muscles and eyes relax, and our brain waves slow down.
This stage is also known as the ‘restorative’ phase of sleep as our body strengthens its immune system and repairs tissues.
When a person sleeps, we experience different stages of the sleep cycle. The deep sleep or slow-wave sleep stage is the most important one as your body needs it to wake up fresh. As we get older, our need for deep sleep decreases. Our bodies become fully developed; thus, we do not require the same growth as children and the duration of deep sleep.
Thus, to understand how much deep sleep or slow-wave sleep one needs, we first need to learn about the different deep sleep stages.
When we sleep, our body cycles through three NREM (Non-Rapid Eye Movement) phases, followed by one REM (Rapid Eye Movement) phase.
Usually, it takes between 90 to 120 minutes to cycle through all four deep sleep stages, after which it starts again.
Adults mostly have 4-6 deep sleep cycles per night. In the first half of the night, a person spends more time in NREM sleep. As the night goes on, we spend more and more time in REM sleep or deep sleep cycle.
NREM First Stage of sleep is brief and drowsy. It gets marked by the transition to sleep when breathing and heartbeat slow down.
This second NREM stage of sleep is where our breathing and heart rate slows down even more. There is a drop in our temperature, and our muscles seem to relax.
Stage 2 of NREM lasts longer in each cycle throughout the night. Every night about half of our sleep is spent in this stage.
Stage 3 of NREM sleep, so called deep sleep, represents the deepest sleep of our sleep cycle when our brain waves are at their highest in amplitude and slowest in frequency.
Deep sleep contributes to insightful thinking, creativity and memory.
During REM sleep, our eyes move quickly beneath the eyelids. At this point of deep sleep, our brain activity is quite similar to that of an awake person.
However, we do not move and lack muscle tone. Most experts believe we dream during REM sleep.
REM sleep is believed to be important for memory, learning and creativity.
Although all sleep stages are necessary for good health, deep sleep or slow-wave sleep offers specific mental and physical benefits.
Our body releases growth hormones essential for immune system functioning and building and repairing muscles, bones, and tissue during deep sleep.
Did you know that elite athletes sleep at least 9 hours every night? It helps them replenish their energy stores.
Deep sleep is vital for cognitive memory and function, and it plays a role in motor skills, language learning, and brain development.
Throughout the day, we process a huge load of information. If we do not rest or get enough deep sleep, our brain cannot process the data properly.
In case you have an important exam, we recommend getting a solid eight hours of sleep to retain whatever you’ve learned and also have energy.
The billion-dollar question is how we can increase our amount of deep sleep? The answer lies in practicing the tips below:
The most common way to get a good night’s deep sleep is enjoying a sweat session daily. People who work out during the day tend to sleep faster than those who do not.
Research also suggests that working out for 150 minutes per week increases your chances of getting deep or slow-wave sleep.
However, avoid intense workouts before bedtime as they can raise your heartbeat, which leads to interrupted sleep.
Ah yes, a warm cuppa java. Did you know your afternoon pick me up could be interfering with your sleep quality?
A study concluded that consuming caffeine seven hours before bedtime reduces the amount of deep sleep you receive by one hour.
Sticking to water, tea, and other decaffeinated beverages are recommended. Some drinks such as warm milk and chamomile tea are also known to improve sleep quality and increase deep sleep.
A healthy diet helps you with weight loss and has an impact on your sleep quality.
Studies have shown that a fibrous diet can lead to more time spent in the deep sleep stage.
During your day, make a conscious effort to add more fiber and sleep-inducing food items to your diet to increase the time you spend in deep sleep.
Not only is yoga an excellent way to center your mind and body, but it also promotes better sleep quality.
A study found that those who practiced cyclic meditation were more likely to experience slow-wave sleep.
Add yoga right before bedtime or to your daily workout routine. Remember to add yoga poses for sleep that help relax the body and mind.
A taxing afternoon with the kids or stress from a busy day can make it difficult to enjoy deep sleep.
Creating a relaxing bedtime routine to curb any looming anxiety and helping your body relax can significantly increase the amount of deep sleep you get.
Our bedtime routine should last anywhere between 30 to 60 minutes, and it should be consistent. It helps one set their mind for sleep and set you up for a productive next day.
The environment in which one sleeps should be sleep-friendly. It means no loud noises, no cold temperature, and bright lights. The best temperature for sleeping is between 17°C to 25°C.
Avoid using electronics at least 1 hour before bedtime. Make use of low, amber light bulbs on your nightstand if you prefer your room dimly lit.
If that does not work, check your bed if your mattress is comfortable.
Pair them with your favorite comforter and plush pillow so that you fall asleep in no time.
Your favorite alcoholic drink might help you go to sleep, but it will interfere with your deep sleep. Our body processes the alcohol we drink before bedtime.
It will diminish any sedative effect and create a rebound effect. Thus, making you wake up in the middle of the night and interrupt deep sleep. If cutting out alcohol before bedtime might seem impossible, we recommend having a drink earlier in the evening.
Sounds can either put you to sleep or give you insomnia. If you suffer due to noisy neighbors or live in the heart of the city, try blocking out any unpleasant noise.
You can do this by earbuds or listening to white or pink noise while falling asleep. Research suggests pink or white sound represents calming nature sounds like steady rainfall or waves crashing on a beach.
Thus, not only helps you fall asleep faster and increases the amount of deep sleep you get.
Like sound, light also has a drastic effect on the quality of deep sleep you get.
If you work night shifts and catch up on your zzz’s during the day or have a partner who enjoys reading at night, using a blindfold will help.
A study conducted on participants found that the use of eye masks resulted in more deep sleep and elevated melatonin levels.
The most common telltale sign that you are not getting enough deep sleep is that you wake up feeling exhausted. When we do not get proper deep sleep, we feel lethargic and groggy.
Deep sleep does wonders for your mental, physical and emotional health. Understanding how deep sleep works helps you identify your sleep problems and how you can fix them.
Take a look at your daily lifestyle, and then fix what you’re doing wrong. If all of that doesn’t work, visiting a sleep specialist can help.
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