Samsung S Health Watch: Accurate Sleep Tracker?

The Samsung Galaxy Watch 5 is a popular smartwatch that can be used to track sleep cycles. It provides a platform for monitoring sleep cycles and additional metrics like blood oxygen levels and other health markers. While no fitness tracker is 100% accurate, the watch provides insights into various sleep stages, including awake, REM, light, and deep sleep cycles. It also offers sleep coaching options and personalized advice to improve sleep habits. The watch's upgraded performance features and continuous contact with the skin enable it to provide more precise sleep statistics.

Samsung Health app features

The Samsung Health app is a comprehensive tool for tracking your fitness and health. It is available for free on Android phones and is compatible with a wide range of other apps and accessories. The app's main features include tracking your daily steps, distance travelled, calories burned, and paths taken—all of which can be viewed on the Health app's main page. Additionally, you can record your meals and nutrients to help manage your weight, and access a range of exercises to suit different intensities and fitness goals.

The app also includes a personal trainer feature, allowing you to set goals and receive advice to stay in shape. It is compatible with various health accessories, such as wearable devices, blood pressure monitors, glucose meters, and heart rate sensors, providing an all-in-one health tracking solution.

One notable feature of the Samsung Health app is its sleep monitoring capability when paired with a Galaxy Watch. The watch uses a combination of sensors, including an accelerometer and thermometer, to track your sleep patterns, sleep quality, and duration. It detects and calculates your sleep cycles, providing a sleep score based on factors such as total sleep time, sleep stages, physical and mental recovery, and interruptions. The app also offers sleep coaching to help you establish a healthier sleep routine.

To use the sleep monitoring feature, you need to enable it in the Samsung Health app and ensure your watch is securely attached to your wrist, positioned correctly for optimal tracking accuracy. The app will then provide detailed sleep data, including sleep time, sleep stages, blood oxygen levels, and snoring detection.

Accuracy of sleep tracking

The Samsung Galaxy Watch uses the Samsung Health app to track and improve your sleep quality. The watch can monitor sleep cycles, showing how long you spend in various sleep stages, including awake, REM, light, and deep sleep. It also monitors blood oxygen levels and can detect snoring. The watch provides a sleep score and offers personalised advice and missions to improve sleep habits.

While Samsung claims that the watch can accurately monitor sleep cycles, it is important to note that no fitness tracker is entirely accurate. A study in 2017 compared a polysomnography with the performance of a Fitbit Charge 2 in 35 adults. The Fitbit detected sleep onset with 96% accuracy but overestimated time spent asleep by 9 minutes on average. It detected light sleep with 81% accuracy, deep sleep with 49% accuracy, and REM sleep with 74% accuracy. A newer study in 2022 found that the Fitbit Alta HR satisfactorily tracked sleep onset, time spent asleep, and sleep cycles.

The accuracy of sleep tracking on the Samsung Galaxy Watch may depend on various factors, such as the fit of the watch. Samsung recommends positioning the watch the width of two fingers above the ulna bone on the wrist. A snug fit improves blood oxygen and heart-rate monitoring and tracking accuracy. The upgraded Samsung Galaxy Watch 5 also has improved accuracy due to continuous contact and upgraded performance features.

Overall, while the Samsung Galaxy Watch may not provide perfectly accurate sleep tracking data, it can still help users spot trends and highlight potential problems with their sleep. The data provided can be used to guide users towards healthier sleeping patterns and track their progress.

Sleep stages and cycles

Sleep is not a uniform process. Instead, a typical night of sleep consists of several rounds of sleep cycles, each composed of four distinct stages. These stages are determined by analysing brain activity during sleep, which reveals distinct patterns that characterise each stage. The four stages of sleep are:

• Non-rapid eye movement 1 (NREM 1) sleep: During this stage, the body has not fully relaxed, and the brain and body activities start to slow down, with periods of brief movements. It is easy to wake someone up during this stage, but if uninterrupted, they can quickly move into the next stage.
• Non-rapid eye movement 2 (NREM 2) sleep: The body enters a more subdued state, with a drop in temperature, relaxed muscles, and slowed breathing and heart rate. Brain waves also show a new pattern, and eye movement stops. Brain activity slows down, but there are still short bursts of activity.
• Non-rapid eye movement 3 (NREM 3) sleep: This is the stage of deep sleep. It is difficult to wake someone up from this stage, and if they do wake up, they may experience "sleep inertia", a state of confusion that can last about 30 minutes.
• Rapid eye movement (REM) sleep: This is the stage where most dreams occur. The eyes move behind closed eyelids, and brain activity resembles that of a waking state. REM sleep makes up about 25% of total sleep time, with the first cycle usually being the shortest, at around 10 minutes.

The first sleep cycle is often the shortest, ranging from 70 to 100 minutes, while later cycles are longer, ranging from 90 to 120 minutes. The duration of each cycle and the time spent in each stage can vary from person to person and from night to night, influenced by factors such as age, recent sleep patterns, and alcohol consumption. On average, a person will experience four to six sleep cycles per night, with each cycle lasting approximately 90 minutes.

Understanding these sleep stages and cycles is important because it helps explain how sleep disorders, such as insomnia and obstructive sleep apnea, can impact an individual's sleep quality and overall health.

Sleep tracking wearables

One popular brand in the sleep tracking space is Samsung, with its Galaxy Watch series. The Samsung Health app, available on the Galaxy Watch, offers sleep monitoring features such as sleep scoring, stage analysis (including REM, light, and deep sleep), snore detection, and blood oxygen monitoring. The watch can also provide personalized advice and missions to improve sleep habits. To enhance tracking accuracy, Samsung recommends positioning the watch snugly on the wrist, with the sensor in contact with the skin, to improve heart rate and blood oxygen monitoring.

The Galaxy Watch 5, in particular, has been noted to provide more accurate sleep statistics due to its upgraded performance features and continuous contact with the user's wrist. The watch offers a simple sleep cycle tracking option, as well as more substantial monitoring tools. Users can access their sleep data directly on the watch or through the Samsung Health app on their connected phone.

Other notable sleep tracking wearables include the Fitbit, which has been studied and found to satisfactorily track sleep onset, time spent asleep, and sleep cycles. The Fitbit Charge 2 detected sleep onset with 96% accuracy but overestimated total sleep time by 9 minutes on average. More recent models, like the Fitbit Alta HR, have shown improved accuracy in tracking light sleep (81%), deep sleep (49%), and REM sleep (74%).

Additionally, the Oura Ring 4 is a competitive sleep tracker that provides insights into sleep efficiency, restfulness, readiness, latency, and more. It claims to accurately track sleep cycles, total sleep time, resting heart rate, heart rate variability, and movement. The Whoop 4.0 is another example of a sleep tracking wearable that provides detailed data and health metrics, helping users improve their sleep and overall health.

Improving sleep quality

While no fitness tracker is 100% accurate, the Samsung Health app and Sleep tile on your Galaxy Watch can help you improve your sleep quality by tracking your sleeping time, recording your snoring, and offering sleep coaching options. The watch tracks your sleep by monitoring your sleep stages, blood oxygen levels, and heart rate. It also provides a sleep score and analyses your sleep consistency.

• Practice relaxation techniques before bed, such as reading a book, taking a hot bath, deep breathing, or visualization.
• Optimize your bedroom environment by minimizing external noise, light, and artificial lights from devices such as alarm clocks. Keep your bedroom at a comfortable temperature, preferably around 65°F (18.3°C).
• Establish a bedtime routine to signal to your body and mind that it's time for sleep. This could include drinking a glass of warm milk, listening to calming music, or any other activity that helps you unwind.
• Get daily sunlight exposure or invest in an artificial bright light device if you don't have access to natural light. Blue light from electronic devices can negatively impact your sleep, so it's important to limit screen time before bed.
• Consider the type of food you eat before bed. High-carb foods tend to have a worse effect on sleep than low-carb options. Also, try to eat dinner at least a few hours before bedtime and limit late-night snacks.
• If you're experiencing persistent insomnia or other sleep disorders, consult a doctor or a healthcare professional for personalized advice and treatment options.

Frequently asked questions