Fitbit's Fee For Viewing Rem Sleep Explained

Fitbit is a popular device used to track sleep in addition to logging steps, calories and cardio. It can monitor the quantity and quality of sleep, which is an important component of health. The device can track the different stages of sleep, including REM sleep, deep sleep and light sleep. While the basic sleep-tracking functions are available through the standard Fitbit app, some features, such as a sleep profile, are only available on Fitbit Premium, which costs $10 a month.

Fitbit's sleep tracking features

Fitbit's sleep-tracking features are designed to give you a detailed look into your sleeping patterns and help you develop healthier habits. The device automatically detects when you're asleep and what stage of sleep you're in by using an accelerometer coupled with a technique called optical photoplethysmography, or PPG. PPG measures blood flow based on how green light from an LED on the back of the watch is reflected by the body. It also uses your movement and heart-rate patterns to estimate your sleep stages.

For more detailed insights, Fitbit offers a premium service that includes a more detailed score breakdown, explanations of why your sleep matters, and tips on how to improve it. Fitbit Premium also provides access to your sleeping heart rate and restlessness, which can give you valuable insights into what is disrupting your sleep. Additionally, with a Premium subscription, you can turn on the snore and noise detection feature to allow the microphone on your Fitbit Sense or Versa 3 to track noise, including snoring.

It's important to note that Fitbit's sleep-tracking features are intended to provide insights into your sleep patterns and are not meant to diagnose or treat any medical conditions. If you have concerns about your sleep health, it is recommended to consult a healthcare professional.

How Fitbit estimates sleep stages

Fitbit estimates sleep stages by using your movement and heart-rate patterns. When you haven't moved for about an hour, your tracker or watch assumes you're asleep. Additional data, such as the length of time when your movements indicate sleep behaviour (like rolling over), help confirm your sleep status.

While you sleep, your device tracks the beat-to-beat changes in your heart rate, known as heart rate variability (HRV), which fluctuate as you transition between light sleep, deep sleep, and REM sleep stages. When you sync your device in the morning, it uses your movement and heart rate patterns to estimate your sleep cycles from the previous night.

Sleep stages are traditionally measured in a lab using an electroencephalogram to detect brain activity, along with other systems to monitor eye and muscle activity. Your Fitbit device can estimate your sleep stages in a more comfortable and convenient way.

Fitbit Versa infers when you're sleeping and what stage of sleep you're in using an accelerometer (an instrument for measuring bodily accelerations of the wrist) coupled with a technique called optical photoplethysmography, or PPG. PPG measures blood flow based on how green light from an LED on the back of the watch is reflected by the body.

Fitbit Premium sleep features

Fitbit Premium offers a range of additional sleep features for subscribers. These include:

• A more detailed breakdown of your sleep score, including an explanation of the score and tips on how to improve your sleep.
• Access to your sleeping heart rate.
• Access to your restlessness data.
• The Restoration score, which is calculated from your heart rate and restlessness data.
• A monthly sleep profile, which is available to Fitbit Premium members using the following devices: Charge 5, Charge 6, Inspire 2, Inspire 3, Luxe, Pixel Watch series, Sense, Sense 2, Versa 2, Versa 3, or Versa 4.
• Snore and noise detection, which allows your Fitbit to track noise, including snoring, in your environment.

Improving your Fitbit Sleep Score

Fitbit's Sleep Score gives you an insight into your sleeping habits and the quality of sleep you get each night. The score is calculated based on several metrics, including the time spent in each sleep stage: REM, light, and deep sleep. Here are some tips to help you improve your Fitbit Sleep Score:

• Set a sleep schedule: Maintaining a consistent sleep schedule is crucial for improving your sleep quality. Set a bedtime and wake-up time that allows you to get seven to eight hours of sleep, which is the ideal duration for most adults. Having a regular sleep schedule will positively affect your mood, concentration, and Sleep Score.
• Exercise regularly: Engaging in regular physical activity can have a positive impact on your sleep. However, try to exercise earlier in the day, as working out too close to bedtime may interfere with your sleep.
• Avoid afternoon naps: While a quick nap may seem tempting, it can disrupt your nighttime sleep and negatively affect your Sleep Score.
• Create a relaxing bedtime routine: Establish a calming pre-sleep routine to help you wind down and prepare for sleep. This could include activities such as reading, meditation, or listening to soothing music.
• Track your caffeine intake: Caffeine consumption can impact your sleep quality. Try to limit your caffeine intake, especially later in the day, as it may make it harder to fall asleep and affect your Sleep Score.
• Use the Relax app: Fitbit offers a Relax app that can help you unwind before bedtime. This app provides guided meditations, sleep aids, and audio tracks to calm your mind and prepare your body for sleep.
• Monitor your sleep heart rate: If you have a Fitbit Premium subscription, you can access your sleeping heart rate data. A higher heart rate during REM sleep may indicate that you are having nightmares, even if you don't remember them the next day.
• Reduce restlessness: Tossing and turning during sleep can lower your sleep quality and make you feel less rested the next day. Try to create a comfortable and relaxing sleep environment to minimise restlessness.
• Improve sleep duration: Aim to get at least seven hours of sleep each night. This will not only improve your Sleep Score but also benefit your overall health and well-being.
• Understand your sleep stages: Benchmark your sleep stages against the averages for your age group. This will help you identify areas for improvement and make necessary adjustments to your sleep habits.
• Address sleep disorders: If you consistently experience high blood oxygen variations during sleep, it may indicate a serious sleep disorder like sleep apnea. Consult a medical professional for further evaluation and guidance.

Fitbit's accuracy and limitations

Fitbit's sleep tracking technology may sound impressive, but there are some limitations that can impact its accuracy and reliability.

Motion Misinterpretation

Fitbit's reliance on motion tracking can lead to inaccuracies. For example, it might interpret periods of restless sleep as periods of wakefulness or classify periods where you are awake but not moving as sleep.

Heart Rate Variability

Your heart rate can vary wildly, even during sleep. As a result, Fitbit's heart rate sensors may struggle to accurately identify sleep stages. For example, your heart rate is likely to be higher if you exercise, eat a large meal, or drink alcohol before bed.

Subjectivity of Sleep Stages

Determining sleep stages using motion and heart rate is a simplified approach. Sleep experts often use electroencephalography (EEG) and other advanced methods to precisely categorise sleep stages. Fitbit's algorithm lacks the depth of information provided by these methods.

Environmental Factors

Fitbit sleep trackers do not consider external factors such as room temperature, noise, or disturbances from partners or pets that can affect sleep quality.

Accuracy

Fitbit sleep trackers tend to overestimate total sleep time by about 10% and underestimate measures of deep sleep and REM sleep by about 20% each. As deep sleep and REM sleep are considered the most important for recovery and memory consolidation, this means your Fitbit is going to tell you your sleep is worse than it actually is.

Fitbit is very accurate at tracking REM sleep and close when it comes to deep sleep. However, it confuses some light sleep with being awake. Overall, Fitbit is 72-73% accurate compared to a professional encephalography (EEG), while the Oura ring v.2 is only 59% accurate.

Limitations

While Fitbit can provide valuable feedback on your sleep, helping you adjust your sleep schedule to get more rest, its accuracy could be better communicated to users. The fact that the SpO2 sensor is not currently used by the app could also be more transparent.

Frequently asked questions