If you use a smartwatch, fitness tracker, or smart ring to monitor your sleep, you may wake up each morning wondering what your sleep score actually means. A number on your app can tell you whether your sleep was “good” or “poor,” but understanding the individual metrics behind that number can give you a much clearer picture of your sleep patterns.
Sleep tracking has become an increasingly popular way to learn more about sleep. Many devices monitor information such as total sleep, sleep efficiency, REM sleep, deep sleep, resting heart rate, and heart rate variability (HRV) to create an overall sleep score.
But what do all these numbers mean? And can your sleep score tell you anything about your mental health?
At Sleep Wellness Center, we help patients understand what may be affecting their sleep and overall well-being. While sleep trackers can be useful for identifying patterns, they are not designed to diagnose sleep disorders. Here's what to know about your sleep score and the metrics behind it.
What Is a Sleep Score?
A sleep score is a number calculated by a sleep-tracking device to summarize different aspects of your sleep. The exact scoring system varies depending on the device, but many sleep trackers consider factors such as:
- Total time asleep
- Sleep efficiency
- Restfulness and nighttime movement
- REM sleep
- Deep sleep
- Sleep latency
- Sleep timing
- Resting heart rate
- Heart rate variability (HRV)
Your device combines some or all of these measurements to create an overall score. It's important to remember that there isn't one universal sleep score that applies to everyone. Different devices use different algorithms and scoring systems, so a score from one brand may not mean the same thing as a score from another.
More importantly, your sleep score should be viewed as a tracking tool rather than a medical diagnosis. Looking at trends over time can be more helpful than focusing on one night's number.
What Does Your Sleep Score Mean?
A sleep score can give you a general idea of how your sleep compares with your usual patterns. A lower score may reflect a shorter night, more nighttime movement, inconsistent sleep timing, or changes in other measurements.
But one low sleep score doesn't necessarily mean something is wrong. You might have a lower score after staying up late, traveling, exercising harder than usual, or having a stressful day. These temporary changes are normal.
What may be more meaningful is a consistent pattern. If your sleep score remains low over time and you're also experiencing daytime fatigue, difficulty concentrating, mood changes, or other sleep symptoms, it may be worth taking a closer look at what's happening.
What Do the Sleep Metrics Mean?
Your overall sleep score is only part of the picture. Understanding the individual metrics can help you better understand what your device is measuring.
Total Sleep
Total sleep is the amount of time you actually spend asleep during the night. Most adults need around seven to nine hours of sleep each night, although individual needs can vary. Consistently getting less sleep than your body needs can affect energy, concentration, mood, and overall health.
If your tracker shows that you're regularly sleeping less than you intended, it may be worth looking at your schedule and sleep habits.
Sleep Efficiency
Sleep efficiency refers to how much of your time in bed you actually spend sleeping. For example, you may spend eight hours in bed but wake up frequently or lie awake for extended periods. In that case, your total time in bed may look adequate while your sleep efficiency is lower.
This metric can be particularly helpful if you feel like you're spending enough time in bed but still aren't waking up feeling rested.
Restfulness
Restfulness generally reflects how much movement or disruption your device detects during sleep. Frequent movement or periods of wakefulness may contribute to a lower restfulness score. However, you may not remember every brief awakening during the night.
A restless night can happen for many reasons, including an uncomfortable sleep environment, stress, illness, alcohol, temperature changes, or an underlying sleep disorder.
REM Sleep
REM sleep, or rapid eye movement sleep, is one of the stages of sleep. It is associated with vivid dreaming and plays an important role in memory, learning, and emotional processing. The amount of REM sleep you get can naturally vary from night to night. Your tracker may estimate how much time you spend in REM sleep based on information such as movement and heart rate.
Because consumer devices do not directly measure brain activity, their sleep-stage estimates are not the same as measurements collected during a clinical sleep study.
Deep Sleep
Deep sleep is a stage of sleep associated with physical restoration and recovery. Like REM sleep, the amount of deep sleep you get can change from night to night. Your age, sleep schedule, overall health, and other factors can influence your sleep architecture.
It's easy to become focused on whether your tracker says you got “enough” deep sleep, but there isn't one perfect number that applies to everyone. Looking at your overall sleep patterns is generally more useful than trying to achieve a specific percentage every night.
Sleep Latency
Sleep latency refers to how long it takes you to fall asleep after going to bed. If you regularly spend a long time awake before falling asleep, several factors could be contributing, including:
- Stress
- An inconsistent sleep schedule
- Caffeine
- Screen use before bed
- An uncomfortable sleep environment
- Insomnia
Occasionally taking longer to fall asleep is normal. Consistently struggling to fall asleep may be worth discussing with a healthcare provider.
Sleep Timing
Sleep timing looks at when you sleep and how consistent your sleep schedule is. Your body relies on an internal clock, or circadian rhythm, to help regulate when you feel awake and when you feel sleepy. Frequently changing your bedtime or wake time can make it harder for your body to maintain a consistent rhythm.
This can be especially important for people who work overnight, rotate between shifts, or have significantly different sleep schedules on weekends.
Resting Heart Rate
Your resting heart rate measures how quickly your heart beats while you are at rest. Your resting heart rate can be influenced by many factors, including sleep, stress, exercise, illness, alcohol, and overall health.
Rather than focusing on one night's reading, pay attention to changes from your normal baseline. A temporary increase doesn't necessarily indicate a problem, but persistent changes may be worth discussing with a healthcare provider.
Average HRV
Heart rate variability (HRV) measures variations in the time between heartbeats. HRV can be influenced by sleep, stress, physical activity, illness, age, and other factors. Importantly, there isn't one HRV number that is considered “good” for everyone.
Your personal baseline and changes over time are generally more useful than comparing your HRV to someone else's.
What Does Your Sleep Score Have to Do With Mental Health?
Sleep and mental health are closely connected. Poor or disrupted sleep can affect how you feel, think, and respond to stress during the day. When sleep is consistently inadequate or fragmented, you may notice:
- Increased irritability
- Difficulty concentrating
- Feeling more stressed
- Changes in mood
- Mental fatigue
- Difficulty managing emotions
The relationship also works in the other direction. Stress, anxiety, and other mental health concerns can make it harder to fall asleep or stay asleep.
This can create a frustrating cycle:
Stress can interfere with sleep → poor sleep can affect your mood and energy → those changes can make the next night of sleep more difficult.
Your sleep score may help you notice these patterns. For example, you may notice that your sleep scores consistently decrease during particularly stressful periods. That doesn't mean your sleep tracker can diagnose a mental health condition. Instead, it can provide another piece of information that helps you recognize how your sleep and daily well-being may be connected.
What Is a Good Sleep Score?
This is one of the most common questions people have about sleep tracking. The answer depends on your device and your individual sleep patterns. There isn't one universal good sleep score that applies to everyone because different devices calculate their scores differently.
Instead of trying to achieve a perfect number every night, consider whether you're consistently:
- Getting enough sleep for your needs
- Maintaining a relatively consistent sleep schedule
- Sleeping without frequent disruptions
- Waking up feeling rested
- Staying alert and functioning well during the day
Your overall health and how you feel during the day matter, too. A high sleep score doesn't necessarily mean you don't have a sleep disorder, and a low sleep score doesn't automatically mean that you do.
Should You Trust Your Sleep Tracker?
Sleep trackers can be helpful, but they have limitations.
Consumer devices use information such as movement, heart rate, and other signals to estimate sleep duration and sleep stages. A clinical sleep study uses specialized equipment to measure things that a smartwatch or ring cannot directly measure, such as brain activity, eye movements, muscle activity, breathing, and oxygen levels.
That means your wearable can be useful for spotting trends, but it shouldn't be used to diagnose a sleep disorder on your own. If your device consistently shows disrupted sleep and you're also experiencing symptoms, those symptoms are worth discussing with your healthcare provider. Read more about the accuracy of sleep trackers >>
When Your Sleep Score May Be Worth Discussing
A sleep score by itself usually isn't a reason for concern. However, persistent changes in your sleep data combined with symptoms may be a sign that it's time to take a closer look at your sleep health. Talk with a healthcare provider if you're regularly experiencing:
- Excessive daytime sleepiness
- Loud or chronic snoring
- Gasping or choking during sleep
- Frequent nighttime awakenings
- Morning headaches
- Difficulty falling or staying asleep
- Difficulty concentrating
- Waking up tired despite getting enough time in bed
These symptoms can have many possible causes, including sleep apnea, insomnia, shift work disorder, restless leg syndrome, and other sleep conditions.
Your Sleep Score Is One Piece of the Puzzle
Sleep tracking can be a useful way to become more aware of your sleep habits. Your sleep score and individual metrics may help you identify patterns in your sleep duration, consistency, restfulness, and other factors.
But the number on your phone doesn't tell the entire story.
If you're consistently getting poor sleep or waking up tired, it's important to look beyond the score and consider how you're actually feeling during the day. Persistent sleep problems may have an underlying cause that a wearable device can't identify.
Sleep Wellness Center offers home sleep studies and in-lab sleep studies to help evaluate symptoms and identify sleep-related breathing problems and other disruptions. If your sleep doesn't feel restorative, even when your tracker says you've had a good night, talking with a sleep professional can help you understand what may really be happening.