Understanding Sleep Data

Sleep is critical to your mental, physical, and emotional well-being. After your sleep session with Muse, you’ll get personalized graphs that give you insights into the quality of your sleep.

Here you'll find a deep dive into the post-sleep session data you get with Muse, so you can understand your sleep data and its changes over time.
 

Sleep Data Summary
Sleep Score
Sleep Stage Data
Slow Wave Intensity
Sleep Position
Heart Rate
Stillness
 

Looking for suggestions on how to create a sleep routine that works for you? Read our Tips on Improving Sleep article.

 

Sleep Session Data Summary

• Sleep Score - measures your sleep efficiency based on the amount of sleep, the time you spend in each sleep stage, and more.

• Sleep Staging - charts how long you’re in light, deep, and REM sleep stages, along with Sleep Assist and Deep Sleep Boost timestamps.

  • Sleep Assist Timestamps - if enabled, orange timestamps on your graph show where Sleep Assist was active to help you sleep.

  • Deep Sleep Boost Timestamps - if enabled, pink timestamps on your graph show where Deep Sleep Boost was active to improve your slow waves.

  • Smart Wakeup Timestamps - if enabled, yellow timestamps on your graph show where Smart Wakeup was active to gently wake you up.

• Slow Wave Intensity - charts the quantity and intensity of your slow waves and how deeply your brain is resting.

• Position Tracking - charts whether you’re a back, side, or front sleeper. See which position helps you get your best rest.

• Brainwave Powerbands - charts your Alpha, Beta, Theta, Gamma, and Delta waves during your sleep session. For more information, see our Brainwave Powerbands article.
  
   

 

Sleep Score

Your Sleep Score is Muse's overall numeric representation of the quality of your sleep. Scored out of 100, your sleep score can provide insight into how your sleep is changing over time without having to look into your data between overnight sessions.

Your score's calculation is first related to your age and gender demographic group. Then, data that influences your score includes:

• How quickly you fall asleep and how long you're asleep.

• How frequently you wake in the night.

• How long you spend in each sleep stage.
   

Sleep requirements are different from person to person, so everyone's Sleep Score is unique to their data. When comparing your sleep score results, look to your previous results and see if there has been a shift. Then you can make intentional adjustments to your day and pre-sleep routine, and track if your sleep score improves.

We find a sleep score of around 75 to be average. Scores above 75 is a good indication of a great night's sleep.
 
💡If you complete more than one sleep session per day, your Sleep Score on the Me screen will display the score you received for the longest session that day.

 

Sleep Stage Data

There are two types of sleep – REM and non-REM. In non-REM sleep, there are three stages you pass through – awake, light, and deep sleep. Each night we cycle through these four stages several times. Non-REM cycles tend to be longer toward the beginning of your sleep, while REM is longer toward the end.
 

Sleep Stage Overview

As you start to fall asleep, you’re between an awake state and light sleep. As you start to drift off, you can awaken easily, and this lasts for only a few minutes. Moving into light sleep, your muscles relax, your body temperature drops, your brain slows, and your eye movements stop.

The next stage of non-REM is deep sleep. Your heart rate and breathing are at their lowest and your muscles are completely relaxed. This is the stage where a lot of restorative processes are at work, such as tissue repair and immune system optimization.

Your REM (Rapid Eye Movement) sleep stage is your dream state. This occurs about 90 minutes after you fall asleep. In this stage, your brain is very active. Your heart rate increases, your breathing speeds up, and your eyes, although closed, start moving rapidly. REM sleep is important for memory, mood, and learning. If you sleep eight hours, you’ll enter REM sleep about five times every 90 minutes or so. On average, we spend the majority of our time in light sleep, approximately 50%, and just 13 to 23% in deep sleep. Finally, REM accounts for approximately 20 to 25%.

The Sleep Stages graph highlights four sleep stages throughout the night: awake, REM, light, and deep sleep.
 

Sleep Stage Graph

The Sleep Staging graph highlights four sleep stages throughout the night: awake, light (N1, N2), deep sleep (N3) and REM, and the number of hours in each stage, to help you understand if you’re getting enough deep sleep and REM sleep. When assessing sleep quality, pay attention to the amount of time you spend in each stage and how this changes over time with your sleep habits and lifestyle choices.

• Awake: Time spent before you fall asleep and anytime you wake in the night. When you're awake, your brain is the most active.

• REM: This stage first occurs about 90 minutes after you fall asleep. Your brain becomes more active compared to the other stages when you're asleep. Your heart rate increases, your breathing becomes faster, and your eyes move rapidly while they are closed (hence the name “rapid eye movement” sleep). This is also the stage where most dreaming occurs and usually where we remember our dreams more vividly.

• Light: Most of your total sleep time is spent in light sleep. In this stage, your muscles relax, your heart and breath rate slow down, your body temperature drops and your eye movements stop. Although your brain activity slows overall, your brain will experience “sleep spindles,” or short bursts of electrical activity that last for less than 2 seconds each. The term spindle is used because the shape of a sleep spindle burst is often like that of a yarn spindle. These are believed to play an important role in organizing your memory.

• Deep: Your brain starts operating more in slower delta waves, and to feel rested in the morning, you need high-quality deep sleep. Your heart rate and breath reach their lowest points during this stage, and your muscles will be fully relaxed. This is where a lot of tissue repair, growth hormone production, and immune system optimization occurs. You’ll be less responsive to your alarm clock, partner, or pet trying to wake you up.
   

Sleep Assist Timestamps

The orange lines at the bottom of the Sleep Staging graph corresponds to when Sleep Assist was activated to help you fall asleep at the start of the session, or when you woke up. If you see Awake sleep staging without the orange timestamps, make sure “Go-back-to-sleep” is enabled on the content you have selected.
 

Deep Sleep Boost Timestamps

It’s important to understand the difference between Deep Sleep stage time and Deep Sleep Boost time.

It’s normal for your Deep Sleep Boost time to be longer than your recorded Deep Sleep (N3) stage time. You may also see Deep Sleep Boost events on nights when little or no Deep Sleep stage is recorded. This happens because Deep Sleep Boost is designed to activate not only when your sleep is classified as Deep Sleep (N3), but more broadly when you’re generating high slow waves. 

Standard sleep stages are determined by the *amplitude* (or height) of your brainwaves. As we age, these brainwave peaks can become less pronounced, even though the brain is still producing meaningful slow-wave activity.

Deep Sleep Boost activates whenever Muse detects increasing or stronger slow waves, including:

• The transition period before you enter Deep Sleep.

• During the period when your sleep is classified as Deep Sleep (N3).

• Periods where slow waves are present but don’t reach the threshold to be labeled as Deep Sleep (N3).
   

In these moments, Deep Sleep Boost is actively reinforcing slow-wave activity. This helps both increase the likelihood of entering Deep Sleep and improve the restorative quality of your Deep Sleep and sleep overall, even if the sleep stage itself isn’t officially classified as N3.

In short, seeing more Deep Sleep Boost time than Deep Sleep stage time means the feature is working as designed, supporting your brain whenever it’s most receptive to deeper, more restorative sleep.

Smart Wakeup Timestamps

The yellow lines at the bottom of the Sleep Staging graph correspond to when Smart Wakeup was activated wake you during your Smart Wake Window.

 

Slow Wave Intensity

The Slow Wave Intensity graph represents your delta wave activity. This graph shows the total power of your brain’s delta wave activity between 1 Hz and 4 Hz. The activity is expected to be greater during deep sleep compared to any other sleep stage. The higher the activity shown on the graph, the greater your slow wave intensity was at that moment.
 

Why is the Deep Sleep stage important?

While deep sleep is key for feeling refreshed, not all deep sleep is created equal. We know that getting enough sleep is crucial for our minds and bodies to repair and recuperate each night. The Delta waves or slow waves of deep sleep have an impact on brain function, physical renewal, hormonal regulation, growth support, mood, immune function, and more.
 

How is Slow Wave Intensity calculated?

Deep sleep points are calculated as the total amount of delta-wave activity measured throughout the night. Even if you don’t get into a deep sleep stage, you are still getting delta waves, and so you're still accumulating slow wave intensity points.

This data allows you to look at the total of the delta wave activity measured throughout the night so you can get a better understanding of how restorative your sleep was. Not all deep sleep moments are equal from a delta-wave perspective. You can compare one deep sleep stage to another, and they may have significantly different intensities, which is accounted for in the Slow Wave Intensity points.

Pay attention to the time of night when your highest peaks happen. For example, if you notice that you don’t get your deepest sleep until much later in the night, you might try adjusting your pre-bedtime routine to help you get into deep slumber sooner.

For more information, take a look at our Deep Sleep blog post.

Tap the Delta δ powerband to isolate it and track the rise and fall of delta waves during your sleep. The brainwave powerband graph in our sleep section is not zoomable at this time but will be available in a future update!

For more information, see our Brainwave Powerbands article.

 

Sleep Position

The Sleep Position graph shows the various sleep positions during the course of the session, including Upright, Left, Back, Right, and Front.

Paying attention to how your sleep position changes throughout the night can help you understand how comfortable or restless your sleep is.

Use your sleep position data to reassess your sleep environment. If you find your sleep quality isn't as strong lately, and you notice you always start your sleep on your back, try a new position to start your sleep and see if your sleep improves.

 

Heart Rate

The Heart Rate graph shows your heart rate measured in beats per minute (BPM) during your session.

Within the same graph, you are also given your average heart rate during your sleep session. Additionally, the green icon on the heart rate graph signifies your lowest measured heart rate for the current session.

Ideally, your heart rate should dip and be the lowest in the middle of your sleep session, which indicates your body is relaxed and will rise to a good night’s rest.

 

Stillness

The Stillness graph shows your bodily movements measured throughout your Sleep session.

Your stillness percentage is a direct reflection of the time you spent being still in relation to the entire length of your session. If you have a stillness score of 45%, it means you were moving 55% of the time.

Your graph is presented with two different areas - Active and Still. Any portion of the line within the active zone means you were likely in search of a comfortable position and areas where the line was in the still zone mean you were in a relaxed position for an extended amount of time. 

It's normal to have periods of movement and restlessness during your sleep. When viewing your Sleep session history, you may notice that periods of increased movement are related to changes in sleep stages.