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Slow-Wave Sleep: How Does It Affect Your Body?

Throughout the night, you go through 4 stages of sleep that each have their own function. Stage three, also called “deep sleep” or “slow-wave sleep,” is one of those stages, and it’s critical for things like cellular repair and muscle and tissue growth and “cleaning out” the brain, among other things.

Here’s everything we need to know about Stage three sleep and how to make sure we’re getting enough.

What happens during Stage 3 sleep?

Stage three sleep falls into the category called ‘deep sleep,’ which focuses on restoring our body. During deep sleep, our body kicks into repair mode, and several things happen, including [1]:

  • The body promotes muscle growth and repair
  • Our blood pressure drops
  • Growth hormone is released
  • Tissue growth and cell repair occurs
  • Blood flow increases to muscles
  • Our brain flushes waste and exhibits long, slow brain waves

What is the purpose of Stage three sleep?

Studies are still being conducted on the benefits of deep sleep for the brain and body; however, there’s proof that the ‘flushing’ that occurs during this stage is needed for ‘cleaning the brain’ and making way for developing new connections moving forward [2].

As far as how the respiratory and heart rates help with this “flushing,” studies are still being conducted there, too, but what you know for certain is that flushing response is most potent during sleep and is a sign that each part of our body is working together during deep sleep to promote repair.

And if you’re missing out on deep slumber, you aren’t giving your body a chance to recover and rebuild from the demands of your day. This is specifically true for athletes who are putting an additional strain on their bodies [3]. 

[Read: Why Proper Sleep Is Important ]

How to know if you’re getting sufficient:

Though the prescribed amount of sleep per night is somewhere around 8 hours, we only spend a small portion of that time in a deep sleep. A good rule of thumb aims for ninety minutes of deep sleep—but the most crucial signal matches our data with how we feel.

If you didn’t get enough, you might experience things like tight muscles, body aches, a persistent feeling of tiredness, and of course, droopy eyelids. As we get to know our body, we’ll learn what amount of deep sleep helps us feel our best. Getting adequate deep sleep helps us wake alert and ready to face the day [4].

Specific patterns to look for include how our body feels after a hard workout, traveling, or when we feel under the weather.

If we notice our body responding by increasing our deep sleep to help us rebound faster, our body responds to stress; If our sleep gets disturbed and we do not have that restorative sleep, it might be a sign to lighten our training or take a rest day.

[Read: How Much Sleep Do We Need]

How to get more Stage 3 sleep:

1. Improve your nighttime routine.

When it comes to receiving quality stage 3 sleep, we’re better off optimizing our regular sleep habits and following good sleep hygiene than trying to play catch up with an occasional extra-lengthy sleep.

Instead of maximizing our deep sleep on a single night, it is more convenient to concentrate on building routines and conditions that frequently return a good amount of deep sleep. Deep sleep tends to take place more in the first half of the night—so ensuring our bedtime routine supports good sleep is critical.

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Besides doing relaxing things to unwind, it helps avoid heavy exercise and heavy meals at least 3 hours before bed, ditch the caffeine later in the day, limit blue light exposure, and set your bedroom temperature to around 65.

2. Try a sleep supporting supplement, like magnesium.

Taking a sleep-aiding supplement like magnesium glycinate before bed can help improve deeper sleep, as it’s been proved to help people fall asleep faster and stay asleep longer.

3. Have a consistent wake/sleep schedule.

And lastly, keeping your wake time and bedtime consistent helps your body get into a natural rhythm. Keeping our wake-up time consistent ensures that about sixteen hours after that, we’re sending our body the same, robust signal: ‘this is the right time to power down.

When our circadian rhythm is strong, it can improve daytime alertness, and it can deepen our sleep and —a win-win. Naps may throw this rhythm off, so it’s an excellent idea to avoid them later in the day and keep the ones we do take short.

[Read: Understanding the Sleep Cycles]

Tips for Improved Sleep

All sleep stages are significant, and our body naturally regulates our sleep cycles to make sure we get what we need.

Check out these patterns to see if the sleep is being disrupted:

Increase in deep sleep after a vigorous workout: Exercise can improve our body’s prioritization of deep sleep the night after a rigorous workout.

1. Higher REM rebound after sleep deprivation

When we recover from a period of sleep deprivation, our body prioritizes deep slumber for the first few nights to repair our body and prepare for action. After numerous nights of sufficient deep sleep, REM sleep rebounds to focus on our brain.

2. Interrupted sleep cycles after caffeine 

Caffeine may increase the time it takes for us to fall asleep, cutting our sleep period short. Shorter sleep periods disproportionately cut down on our total REM sleep, as REM cycles are more likely to occur in later sleep cycles.

You all have those days when you “simply need your coffee.” However, taking a look at our nightly patterns (e.g., body temperature, heart rate) and acting on our desire to improve our sleep can help you face those days well-rested.

Bottom Line

There’s no magic potion to getting more deep sleep; When it comes to being energized regularly and well-rested, consistency is vital. But if we continually pay attention to our sleep hygiene, not only will we get restorative slow-wave sleep, but we’ll feel energized when we wake, too.