Garmin's Rem Sleep Tracking: How Accurate Is It?

Sleep tracking is a feature of many Garmin devices, but how accurate is it? According to some users, not very. One user compared their results with a Fitbit Ionic and found that the Fitbit was vastly more accurate. Another user compared their results with an Oura ring and found huge differences, concluding that you cannot really trust any of the Garmin's sleep metrics if you are looking for accuracy.

However, one user found that their REM sleep correlates fairly well with their dreams and stress levels, and another found that their device was definitely getting whether I have deep sleep or not.

Research over the past few years suggests that sleep tracking devices are about 78% accurate in measuring sleep versus awake time, and only about 38% accurate in measuring how long it takes to fall asleep.

A 2020 study tested the performance of seven consumer sleep-tracking devices, including two Garmin devices, against polysomnography (PSG), the gold-standard sleep assessment technique. It found that the Garmin devices performed worse than actigraphy, a research-grade wrist-worn device, in detecting sleep and wake. The study also found that the devices tended to perform worse on nights with disrupted sleep.

In summary, while some users find their Garmin's sleep tracking useful, others are less convinced. The available research suggests that sleep tracking devices are not very accurate, and that the Garmin devices tested were outperformed by competitors.

Garmin's sleep tracking accuracy is questioned by many users

In addition, some users have pointed out that Garmin's sleep tracking seems to be based primarily on movement and does not adequately incorporate other factors such as heart rate variability (HRV) or heart rate (HR). This can lead to inaccuracies, such as the device registering periods of wakefulness when the user is actually asleep and vice versa. Some users have also observed that their Garmin devices often fail to detect daytime sleep or naps.

A study published in the journal Sleep that evaluated the performance of seven consumer sleep-tracking devices, including two Garmin models (Fenix 5S and Vivosmart 3), found that the Garmin devices performed worse than actigraphy, a standard mobile sleep assessment technique, in detecting sleep/wake patterns. The study also noted that the devices tended to perform worse on nights with disrupted sleep.

Mathew Walker, a sleep scientist who has worked with various wearable companies, is quoted as saying that the better devices are only about 60% accurate and that it will take a few years for them to match the accuracy of an actual sleep study.

Despite these concerns, it is important to recognize that sleep tracking is a complex task, and no device can currently offer perfect accuracy. Additionally, individual variations, such as sleeping patterns and heart rate, can also impact the accuracy of sleep tracking devices.

REM sleep accuracy is often incorrect

Sleep tracking accuracy is often incorrect, and this is true for many consumer devices, not just Garmin. The accuracy of sleep tracking devices is a widely discussed topic, with many users expressing their views on forums and review sites.

Garmin's sleep tracking feature has been described as "fairly inaccurate" by some users, who claim that it is based solely on movement and does not incorporate other data such as HRV or HR. One user compared the sleep data from their Garmin device with that of an Oura ring, which they considered to be extremely accurate, and found "huge differences" between the two. They noted that Garmin classified periods of wakefulness as light sleep and vice versa. Another user stated that their Garmin device detected REM sleep when they were awake.

A study published in the National Library of Medicine (NLM) compared the performance of seven consumer sleep-tracking devices, including two Garmin models, against polysomnography (PSG), the gold standard for sleep assessment. The study found that the Garmin devices performed worse than actigraphy, a research-grade wrist-worn device, in detecting sleep/wake patterns. The study also found that the devices tended to perform worse on nights with disrupted sleep.

Mathew Walker, a sleep scientist, has stated that the better sleep-tracking devices are only about 60% accurate and that it will take a few years for them to become as good as an actual sleep study.

Despite these inaccuracies, some users have found that their Garmin device's REM sleep data correlates fairly well with their remembered dreams and overnight stress with alcohol consumption. Additionally, one user noted that their device's sleep score seemed to reflect how they felt the next day.

It is worth noting that sleep tracking is a challenging task, and even PSG, the gold standard technique, has its limitations. Consumer devices, such as those from Garmin, offer a convenient way to track sleep patterns and can provide valuable insights, even if they are not 100% accurate. However, it is important for users to be aware of the limitations of these devices and not rely solely on them for sleep monitoring.

Sleep tracking is based on movement and heart rate

Sleep tracking devices such as the Garmin watch measure your heart rate and motion to estimate your sleep stages. However, the accuracy of these devices is questionable. According to a study that compared the performance of a Fitbit Charge 2 with polysomnography (PSG) in 35 adults, the Fitbit detected sleep onset with 96% accuracy but overestimated time spent asleep by 9 minutes on average. In the same study, Fitbit detected light sleep with 81% accuracy, deep sleep with only 49% accuracy, and REM sleep with 74% accuracy.

Another study published in 2022 compared the performance of Fitbit Alta HR to an EEG conducted simultaneously on 40 college athletes while sleeping. This study found that Fitbit data satisfactorily tracked sleep onset, time spent asleep, and sleep cycles. While not 100% accurate, the Fitbit data had a strong correlation with PSG data.

In terms of the Garmin watch specifically, user reviews are mixed. Some users report that their Garmin watch accurately tracks their sleep, while others claim that it often thinks they are asleep when they are awake or gaming. One user compared their Garmin Forerunner 55 with a Fitbit Blaze and found that the Fitbit was far more accurate in tracking their sleep times.

Overall, while sleep tracking devices like the Garmin watch can provide insights into your sleep patterns, they should not be relied upon as completely accurate. For a truly accurate measurement of your sleep stages, a polysomnography test that measures brain waves, heart rate, breathing, blood oxygen levels, and eye movements is necessary.

Fitbit is considered more accurate for sleep tracking

Sleep tracking has become an important feature for many fitness tracking devices, with Fitbit and Garmin being two of the most popular brands. While both companies offer sleep tracking capabilities, there are some who consider Fitbit to be more accurate when it comes to monitoring sleep.

One of the key advantages of Fitbit's sleep tracking is its ability to track short naps during the day. This is a feature that Garmin devices lack, as they do not support nap tracking. Fitbit's sleep tracking also provides more detailed statistical data about your sleep, including a breakdown of the different phases of sleep: light sleep, deep sleep, and REM sleep. This allows users to gain deeper insights into their sleep patterns and make more informed decisions about their sleep habits.

In addition, Fitbit's sleep tracking feature, known as Sleep Score, utilizes a combination of data points such as heart rate, sleep time, breathing, and restlessness to provide a comprehensive analysis of sleep quality. The scoring system simplifies the statistical data, making it easier for users to understand their sleep patterns at a glance. This feature is particularly useful for those who want a quick and accessible way to track their sleep.

Moreover, Fitbit devices have been praised for their accuracy in detecting sleep and wake times, even when waking up in the middle of the night. This level of precision is not always found in Garmin devices, which may continue to track sleep even when the user is awake and inactive. Fitbit's accuracy in this regard may be due to its ability to detect changes in heart rate and movement that indicate a shift from sleep to wakefulness.

While both Fitbit and Garmin offer sleep tracking capabilities, user experiences and reviews suggest that Fitbit may have an edge when it comes to accuracy and detailed insights. However, it is important to note that no consumer sleep tracking device can match the accuracy of a professional polysomnography test, which remains the gold standard for measuring sleep stages and sleep quality.

Sleep tracking is a marketing feature

Sleep tracking is a relatively new feature that has been incorporated into many devices, such as smartphones, smartwatches, and fitness trackers. It is marketed as a way to help individuals monitor their sleep patterns and improve their sleep quality. While it may be a useful tool for some, it is important to recognise its limitations and accuracy.

The accuracy of sleep tracking devices has been questioned by many users. Online forums are filled with people comparing their experiences with different devices, such as Garmin, Fitbit, and Apple Watch. Some users have found that their sleep tracking devices often mistake periods of inactivity or relaxation for sleep. For example, a user on the Garmin forum noted that their device registered them as sleeping when they were simply lying down and reading a book. Another user on Reddit mentioned that their Garmin watch thought they were asleep when they were actually working at their computer. These anecdotes highlight the potential inaccuracies of sleep tracking devices and their reliance on movement and heart rate data to estimate sleep.

Research studies have also evaluated the accuracy of sleep tracking devices. One study found that the Garmin Forerunner 945 and Polar Ignite multisport activity trackers overestimated light sleep and underestimated deep sleep when compared to polysomnography (PSG), which is considered the gold standard for sleep measurement. Another study suggested that sleep tracking devices are about 78% accurate in measuring sleep versus awake time but only about 38% accurate in measuring how long it takes to fall asleep. It is important to note that sleep tracking devices measure heart rate and motion to estimate sleep stages, while PSG measures brain waves, heart rate, breathing, blood oxygen levels, and eye movements.

Despite the limitations and accuracy concerns, sleep tracking can still be a valuable tool for some individuals. It can help users recognise patterns in their sleep habits and make adjustments to improve their sleep quality. For example, a user on Reddit shared that their sleep tracker helped them discover that they slept better when their bedroom was cooler. Additionally, sleep tracking can be a fun way to gain insights into your sleep patterns and make adjustments to your routine. However, it is important to remember that sleep tracking should not be used as a substitute for professional medical advice or diagnosis. If you have significant sleep issues or concerns, it is best to consult a healthcare professional.

In conclusion, while sleep tracking can be a useful and interesting feature for some individuals, it is important to recognise its limitations and accuracy. It should be used as a tool to help improve your sleep habits and gain insights into your sleep patterns, rather than as a medical device.

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