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What is Deep Sleep? How Smartwatch Detects Deep Sleep?

Sleeping is very necessary to keep our body and mind relaxed and working. Thankfully, the modern-day smartwatches can detect our sleep, alongside different stages, including light and deep sleep. Therefore, in this article, we will see what deep sleep is, how it is different from light sleep, and how a smartwatch detects deep sleep and its various stages. Read on.

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What is Deep Sleep?

What is Deep Sleep

Deep sleep is the third stage of the Non-REM sleep cycle. This is the highest stage of sleep in which your brain waves comes down to the slowest during whole sleep. This is when your body muscles relax, and your heartbeat and breathing become slowest.

During deep sleep, it is very hard to get awake, even with loud noises around you. Deep sleep is also known as slow-wave sleep (SWS) or delta sleep. The first deep sleep stage can last anywhere between 45-90 minutes. It lasts for a longer period in the first half of the night and gets shorter as the time goes on.

Advantages of Deep Sleep

  • Relaxes Muscles and Brain
  • Body Feels Light
  • Restores Energy
  • Strengthens Immune System
  • Increases Blood Supplies to Muscles

How a Smartwatch Detects Deep Sleep?

How Smartwatch Detects Deep Sleep

The smartwatches track your sleep with the help of a gyroscope, accelerometer, and heart rate monitor. The gyroscope and accelerometer sensors help track your wrist movements through which it detects whether you are sleeping or awake.

After that, smartwatches also use the heart rate monitor to detect your heartbeat during sleep. It helps the smartwatch to check which sleep cycle you are in. And as we know that during deep sleep, our heartbeat slows down to the lowest, allowing it to track and detect our deep sleep. This is how a smartwatch detects and tracks deep sleep.

You can check your light sleep, deep sleep, and different sleep cycles on your smartwatch, depending on the features. In some smartwatches, you can also look for how much time you are awake in between your full sleep.

Different Stages of Sleep Cycles

Stages of Sleep

There are different stages of sleep cycles that include rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. And since deep sleep is part of NREM sleep, we will also talk about that.

1. NREM Stage 1

This is the first stage of the sleep cycle in which your body enters the sleep, and you are in between the wakefulness and sleep condition. In this stage, your muscles and brain slow down and relax.

Your breathing, heartbeat, and eye movement slow down, entering light and relaxed environment. But, if someone disturbs you a bit or any loud sound happens around you, you may wake up easily.

2. NREM Stage 2

According to American Sleep Foundation, people spend about 50% of their sleep in this stage. It lasts for up to 20 minutes per sleep cycle in NREM Stage 2. In this stage, you become less aware of your surroundings, and normal sounds may not affect your sleep.

Your body temperature drops, and your eye movement stops gradually. Also, your breathing and heart become more regular. Your brain starts gathering, processing, and filtering the previous day’s memories.

3. NREM Stage 3

This is when your brain, muscles, and heartbeat slows down to the lowest. It is when any background noises or activity in the environment may not wake up the sleeping person. A person should take enough of the NREM Stage 3 sleep for a relaxed and refreshed body the next day.

In this stage, your body starts its physical repairs, and your brain consolidates some crucial memories like personal experiences, general knowledge, and other experiences.

4. REM (Rapid Eye Movement) Sleep

Rapid Eye Movement is the final stage of sleep in which your voluntary muscles become immobilized. During this stage, your brain acts closely as it does in the active hours.

This is the stage when you see dreams, your breathing gets faster and irregular, and your body temporarily gets paralyzed, which also prevents your body to act on your dreams. In this stage, your emotions and emotional memories are processed and stored.

Light Sleep vs. Deep Sleep

Light vs Deep Sleep Smartwatch

Light sleep is the starting stage of the sleep cycle, whereas deep sleep is the most important stage to repair the body overnight. Light sleep can generally be seen in starting your night sleep, a small nap during the day, or during travel. Deep sleep happens only during the full sleep cycle at night after the first half of the whole sleep.

Deep sleep is necessary to take once every day to relax all body muscles and prepare the body for new challenges. Light sleep or a small nap may keep you relaxed during the daytime.

Light sleep is the stage when you are in between awake and sleep conditions. It means that you wake up easily by any small sound in your surroundings. Whereas during deep sleep, your body relaxes at the extreme stage, and no loud noises or sounds may awake you during this stage.

So, light sleep is the starting stage of the sleep cycle, and as you sleep for long, you enter the deep sleep stage.

Related | 5 Ways To Stop Your Smartwatch Notifications While Sleeping At Night

Tips to Increase Your Deep Sleep

Increase Your Deep Sleep

There are several ways that you can use to increase your deep sleep. Taking enough deep sleep is necessary for a healthy and refreshed body, so here are some things that you can do to increase it:

  • Workout Daily
  • Eat More Fiber-rich Food
  • Do Yoga and Meditation
  • Avoid Caffeine 7+ Hours Before Sleeping
  • Create Relaxing Bedtime Routine
  • Keep Bedroom’s Environment Restful
  • Listen to Soothing Sounds Before Sleep
  • Use Eye Mask to Keep Lights Away From Eyes

Wrapping Up

This was all about deep sleep and how a smartwatch detects it. I hope you got to know all the important things about deep sleep, different sleep cycles, and its benefits. You can track your deep sleep timings through the smartwatch while wearing it during sleep. How do you like this article? Tell us in the comments below, and stay tuned with WearablesToUse for more informative articles!


Himanshu Kansal

Himanshu roams around the Internet to find the latest happenings in Tech Industry to stay updated about everything Tech. Apart from being a Tech Writer, he also makes content on YouTube and is passionate about Smartphones and Gadgets.