You Want To Make Sure You're Getting Enough Slow-Wave Sleep — Here's Why
Throughout the night, we go through four stages of sleep that each have their own function. Stage 3, also known as "slow-wave sleep" or "deep sleep," is one of those stages, and it's vital for things like muscle and tissue growth, cellular repair, and "cleaning out" the brain, among other things. Here's everything you need to know about Stage 3 sleep, plus how to make sure you're getting enough.
What happens during Stage 3 sleep?
As Hannu Kinnunen, chief science officer at Oura, explains to mbg, "Stage 3 sleep falls into the category known as 'deep sleep,' which focuses on restoring your body." During deep sleep, he says, your body kicks into repair mode and a number of things happen, including:
- Your blood pressure drops
- The body promotes muscle growth and repair
- Blood flow increases to muscles
- Growth hormone is released
- Tissue growth and cell repair occurs
- Your brain flushes waste and exhibits long, slow brain waves
What is the purpose of Stage 3 sleep?
According to Kinnunen, research is still being conducted on the benefits of deep sleep for the body and brain, however, "there's evidence that the 'flushing' that occurs during this stage is necessary for 'cleaning the brain' and making way for building new connections moving forward."
As far as how heart and respiratory rates help with this "flushing," research is still being conducted there, too, "but what we know for sure is that flushing response is strongest during sleep and is a sign that every part of your body is working together during deep sleep to promote repair," Kinnunen explains.
And if you're missing out on deep sleep, you aren't giving your body a chance to rebuild and recover from the demands of your day, he adds. "This is especially true for athletes who are putting extra strain on their bodies."
How to know if you're getting enough.
Though the recommended amount of sleep per night is somewhere around eight, hours, we spend only a small portion of that time in deep sleep. "A good rule of thumb is to aim for 90 minutes of deep sleep—but the most important signal is matching your data with how you feel," Kinnunen notes.
If you didn't get enough, you may experience things like body aches, tight muscles, and of course, droopy eyelids and a persistent feeling of tiredness. "As you get to know your body, you'll learn what amount of deep sleep helps you feel your best," he adds. "Getting enough deep sleep helps you awaken alert and ready to face the day."
Certain patterns to look for include how your body feels after a hard workout, traveling, or when you feel under the weather, Kinnunen says. "If you notice your body responding by increasing your deep sleep to help you rebound faster, your body is responding to stress," he explains, adding, "If your sleep gets disturbed and you're not getting that restorative sleep, it could be a sign to lighten your training or take a rest day."
How to get more Stage 3 sleep:
1. Improve your nighttime routine.
When it comes to getting quality Stage 3 sleep, you're better off optimizing your regular sleep habits and practicing good sleep hygiene than trying to play catch up with an occasional extra-long sleep.
"Instead of maximizing your deep sleep on a single night, it is more favorable to concentrate on building routines and conditions that support a good amount of deep sleep regularly," Kinnunen says. "Deep sleep tends to occur more in the first half of the night—so ensuring your bedtime routine supports good sleep is key."
Along with doing relaxing things to unwind, he says it helps to avoid heavy meals and heavy exercise at least three hours before bed, ditch the caffeine later in the day, limiting blue light exposure, and setting your bedroom temperature to around 65.
2. Try a sleep-supporting supplement, like magnesium.
Taking a sleep-supporting supplement like magnesium glycinate before bed may help promote deeper sleep, as it's been shown to help people fall asleep faster and stay asleep longer.*
The deep and restorative sleep you've always dreamt about*
3. Have a consistent sleep/wake schedule.
And lastly, keeping your bedtime and wake time consistent helps your body get into a natural rhythm, Kinnunen says. "Keeping your wake-up time consistent ensures that about 16 hours thereafter, you're sending your body the same, strong signal: 'this is the right time to power down,'" he notes. When your circadian rhythm is strong, it can deepen your sleep and improve daytime alertness—a win-win. He also notes naps can throw this rhythm off, so it's a good idea to avoid them later in the day and keep the ones you do take short.
The bottom line.
There's no magic secret to getting more deep sleep; when it comes to being well rested and energized on a regular basis, consistency is key. But if you continually pay mind to your sleep hygiene, not only will you get restorative slow-wave sleep, but you'll feel energized when you wake, too.