Active 2 Sleep Tracker: How Reliable Is It?

Sleep trackers have become increasingly popular, with one in three people reporting regular sleep complaints. While they can be useful for those who generally sleep well but want to track their sleep or establish a better routine, their accuracy has been called into question. Sleep trackers are worn on the wrist and make their estimates of nightly sleep by measuring body movement and sometimes heart rate data. Research has found that compared to polysomnography tests, which are used to diagnose sleep disorders, sleep trackers are only accurate 78% of the time when identifying sleep versus wakefulness. This accuracy drops to around 38% when estimating how long it took participants to fall asleep. The Samsung Galaxy Active 2 uses your movement and heart rate to track your sleep, and reviews are mixed on its accuracy. While some users have found it to be consistently accurate at recording how long they slept, others have found it to be inaccurate.

Accuracy of sleep tracking

Sleep tracking devices have gained popularity in recent years, with many people wanting to understand their sleep patterns better. However, only a few studies have investigated the accuracy of these devices. Sleep trackers are worn on the wrist or finger and make their estimates of nightly sleep by measuring body movement and sometimes heart rate data.

The Samsung Galaxy Active 2 watch uses your movement and heart rate to track your sleep. It has been found to be consistently accurate at recording how long a person slept and at catching when they take a nap. However, it records the time spent lying in bed before and after sleep as "Awake" and as part of the total sleep time. It also uses location data via GPS to determine when the user is no longer asleep. The Samsung Health app provides additional sleep metrics such as sleep stages (awake, REM, light, and deep), efficiency percentage, calories burned, consistency targets, averages, and trends over time.

The accuracy of sleep trackers is an important consideration, especially when compared to polysomnography tests, which are considered the gold standard for diagnosing sleep disorders. Sleep trackers are only accurate 78% of the time when identifying sleep versus wakefulness, and this accuracy drops to around 38% when estimating how long it took participants to fall asleep. Watches that incorporate heart rate data tend to be slightly more accurate when measuring sleep duration because heart rate fluctuates during different sleep stages. However, even devices that track heart rate may underestimate the amount of deep sleep obtained by as much as 46 minutes.

The Oura Ring Gen3 is another sleep tracker that has been found to provide consistently accurate heart-rate data. It uses infrared (red and green LED light) beams to measure respiratory rate, heart rate, heart rate variability, blood oxygen levels, and body temperature. When tested against a heart-rate sensor, the Oura Ring proved to be the most accurate. Oura's validation study shows that its HRV measurements are 98.4% accurate when compared to an electrocardiogram.

Despite the improvements in accuracy, it is important to note that no commercially available sleep tracker can perfectly analyze your sleep or diagnose a sleep disorder. Sleep trackers should be used as a tool to identify trends in your sleep, monitor your activity and heart rate, and provide guidance on improving your rest and fitness.

Heart rate and movement tracking

The Samsung Galaxy Active 2 uses your movement and heart rate to determine whether you are awake or in the light, deep, or REM sleep phases. This data is tracked in the Samsung Health app, which can be viewed on the watch but is recommended to be viewed on a smartphone.

Sleep trackers have a history of being inaccurate. A 2017 article from The Mayo Clinic mentions that "more than 20 research studies have examined the accuracy and validity of the sleep information they generate. The results show that, ... the devices are largely inaccurate." However, some people believe that sleep trackers have improved since then.

The Samsung Galaxy Active 2 has been found to be consistently accurate at recording how long one has slept and at catching when one takes a nap. However, it does not always accurately track the difference between deep sleep and light sleep. It also records the time spent lying in bed awake in the morning as "Awake" and as part of total sleep time. This time is deducted from the "Actual sleep time." It is suspected that the watch also uses one's location, via GPS, to determine when one is no longer asleep.

The Samsung Health app tracks a lot more information besides sleep, including movement and activity and a range of other metrics such as heart rate, heart rate variability, body temperature, blood-oxygen rate, and menstrual cycles.

Comparison to polysomnography tests

The accuracy of sleep trackers is often evaluated by comparing them to polysomnography (PSG) tests, which are considered the gold standard in sleep measurement. PSG involves monitoring various physiological parameters, such as brain activity, eye movement, muscle activity, and breathing, to provide a comprehensive assessment of sleep quality.

Sleep tracking and mental health

Smartphones and wearables, such as the Samsung Galaxy Active 2, have become increasingly popular tools for tracking sleep. The Samsung Galaxy Active 2 uses movement and heart rate data to track sleep, and while it may not be entirely accurate, especially for individuals with sleeping problems, it can provide a close estimation of sleep patterns. Other wearables, like the Oura Ring, have been found to offer consistently accurate heart rate data and easy-to-follow guidance, aiding users in understanding their sleep patterns and making improvements.

The ability to collect data on sleep duration and quality through these devices can be beneficial for those with psychiatric disorders, who often experience sleep problems. For example, wrist-worn devices can capture movement patterns during sleep, and this data can be used to monitor sleep and associate it with various mental health conditions. While polysomnography, which involves recording brain waves, blood oxygen, heart rate, breathing, and movement, is a traditional method for monitoring sleep, it requires specialized equipment and is not practical for large-scale at-home monitoring.

Despite the limitations in clinical evidence, the use of smartphones and wearables for sleep tracking in mental health holds promise. These technologies can help integrate sleep monitoring into the daily lives of individuals with psychiatric disorders, providing insights into sleep quality, patterns, and their relationship with mental health symptoms. Additionally, as methods for collecting and analyzing sleep data improve, we can expect to gain a better understanding of the relationship between sleep and mental health, potentially leading to more effective interventions and treatments.

Sleep tracking accuracy in Samsung watches

Sleep tracking accuracy is an important aspect of wearable health technology, and Samsung has been working on improving its sleep tracking capabilities. The Samsung Galaxy Active 2 watch uses movement and heart rate data to track sleep. This method of tracking sleep has been found to be quite accurate by many users, especially for healthy individuals. However, the accuracy may decrease for individuals with sleeping problems or irregular heart rates.

The watch accurately records the duration of sleep and can even detect short naps. It differentiates between "Awake" and "Light Sleep" and stages, although the distinction between light and deep sleep may not always be precise. The watch's accuracy is also affected by factors such as morning routines, as it may record lying in bed and checking emails as "Awake" time, which is then deducted from the "Actual sleep time".

In a comparative study of 11 consumer sleep trackers (CSTs), the Samsung Galaxy Watch 5 was included and showed promising results. It was among the top 5 CSTs with the highest macro F1 scores for REM stage accuracy, along with the Google Pixel Watch, Fitbit Sense 2, Amazon Halo Rise, and SleepRoutine. However, it is important to note that no commercially available sleep tracker can perfectly analyse sleep or diagnose sleep disorders; for that, a professional sleep lab is required.

User experiences with the Samsung Galaxy Watch have been generally positive regarding sleep tracking accuracy. One user shared their experience of having a sleep study done in a hospital, and the results aligned with the data from their Samsung watch. Another user mentioned that their watch accurately reflected their good and bad nights of sleep, with data on "awake" and "light sleep" time matching their personal assessment of their sleep quality.

In conclusion, while sleep tracking technology has its limitations and may not be as accurate for individuals with sleep issues, the Samsung Galaxy Active 2 watch has received positive feedback for its sleep tracking capabilities. It effectively uses movement and heart rate data to provide insights into sleep patterns, helping users understand their sleep quality and make informed decisions to improve their rest.

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