Sleep Tracking Bands: Understanding Their Functionality And Mechanism

Sleep tracking bands are wearable devices that monitor your sleep patterns and provide insights into your sleep quality. They can be strapped to your wrist, clipped to your pillow, or placed on your bedside table. While they don't directly measure sleep, they estimate it by tracking inactivity and detecting interrupted sleep. Some popular sleep tracking bands include the Oura Ring, Whoop Band, and Biostrap Kairos. These devices use sensors to measure heart rate, respiratory rate, sleep phases, and other metrics to give you a sleep score and help you optimize your sleep habits.

Sleep tracking bands monitor sleep duration, quality, and phases

Sleep tracking bands work by measuring sleep through various metrics, such as heart rate, sleep efficiency, respiratory rate, blood-oxygen levels, body temperature, and movement. Some trackers also take into account lifestyle factors, such as caffeine intake, diet, and stress levels. The data collected by these sensors is then processed to produce reports on your sleep cycle, heart rate, and breathing, often accompanied by an overall sleep score. This score is calculated based on factors such as sleep efficiency, temperature, restfulness, consistency, total sleep, and heart rate drop.

The Oura Ring, for example, is a popular sleep tracking band that measures metrics such as respiratory rate, heart rate, heart rate variability, blood oxygen levels, and body temperature. It combines sleep data with activity data collected by an accelerometer to provide insights into your sleep and energy output. The Oura Ring also offers personalised advice and features a body clock tool that teaches users about their body clock and sleep chronotype.

Another example is the Whoop band, which is a lightweight, screenless band that tracks sleep data. It measures heart rate, respiratory rate, blood oxygen levels, and skin temperature. The Whoop band also includes a sleep coach feature, which informs users of optimal sleep times based on their data. This band is designed for active people and can be worn as a wristband or attached to different garments, such as sports bras or leggings.

It is important to note that sleep tracking bands do not directly measure sleep. Instead, they estimate sleep by measuring inactivity and making guesstimates about actual sleep time. For exact data about sleep habits, a medical sleep study that monitors brain waves is required.

They measure heart rate, respiration, and HRV

Sleep-tracking bands can measure heart rate, respiration, and HRV (heart rate variability) to provide insights into sleep quality and overall health and wellness. HRV is a measure of the variation in time between each heartbeat. This variability is influenced by the sympathetic nervous system, which increases heart rate in response to stress or high activity levels, and the parasympathetic nervous system, which slows down the heart rate during rest or digestion. By tracking HRV, individuals can identify habits that may be causing sleep issues and make changes to improve their sleep quality.

The Oura Ring Gen3, for example, uses infrared LED lights and sensors to measure heart rate, HRV, respiratory rate, blood oxygen levels, and body temperature. It combines sleep data with activity and movement data to provide daily scores for sleep, activity, and readiness. The Whoop wristband, on the other hand, uses photoplethysmography (PPG) and LEDs to detect blood volume levels and calculate heart rate and HRV. It also measures the intensity of activities and provides detailed recommendations for improving fitness.

Sleep tracking bands can help individuals identify patterns and habits that impact their sleep. For example, by reviewing data from periods of good sleep, individuals can establish a baseline for the ideal amounts of time spent in each sleep stage. If they notice deviations from this baseline, they can investigate the behaviours or factors that may be affecting their sleep. This information can be used to make informed decisions and improve sleep quality.

Additionally, sleep tracking bands can provide insights into respiratory rate, which is important for individuals concerned about their breathing during sleep. By tracking respiration, individuals can monitor for any breathing abnormalities or disruptions that may impact their sleep quality or overall health. Overall, the ability to measure heart rate, respiration, and HRV allows sleep tracking bands to offer valuable data and guidance for optimising sleep and enhancing overall wellness.

They use PPG and LED lights to detect blood-volume levels

Sleep-tracking bands use photoplethysmography (PPG) and light-emitting diodes (LED) lights to detect blood-volume levels. PPG is a technology that uses light to detect blood flow and volume. As light passes through tissue, it is absorbed and reflected in different ways depending on the density of the tissue and the presence of blood flow. By analysing the way light is reflected and absorbed, PPG can detect changes in blood volume and flow. This is then used to calculate heart rate and heart-rate variability, which are used to track sleep.

The Whoop band, for example, uses PPG and LEDs to shine a light on your skin. It then translates the differences in light absorption and reflection into changes in blood flow, which is how it calculates heart rate and heart-rate variability. The Whoop strap also uses an accelerometer to track motion, which, along with the PPG and the Whoop device’s “trademarked algorithm”, makes it possible for the tracker to determine your sleep stages.

The Oura Ring Gen3 also uses red and green LED light beams and sensors to measure your respiratory rate, heart rate, heart-rate variability (HRV), blood-oxygen levels, and body temperature. It uses those metrics to track your sleep, and an accelerometer logs your activity and movement. It then synthesises the two chunks of data—your sleep versus your energy output—to give you three daily scores: Sleep, Activity, and Readiness.

The Ultrahuman Ring Air uses infrared PPG sensors, red LEDs, and green LEDs for heart rate monitoring and oxygen saturation.

PPG and LED lights are also used in other wearable health-tracking devices, such as the Biostrap Kairos and the Google Pixel Watch 2, to track heart rate and blood oxygen saturation.

They can be worn on the wrist, clipped to a pillow, or placed on a bedside table

Sleep tracking bands can be worn in different ways to monitor your sleep. The most common type is a wristband, but some trackers can also be clipped to your pillow or placed on your bedside table.

Wristbands are typically lightweight and screenless, with some designed to look like stylish accessories, while others are more reminiscent of athletic bands. They can monitor your sleep by tracking your heart rate, respiration, and heart-rate variability (HRV). Some also track your body temperature and blood oxygen levels. The data collected by these devices can be used to provide tailored insights into your sleep quality and duration, as well as identify any sleep problems you may have.

The Oura Ring, for example, is a titanium, wedding-band-shaped device that shines infrared light beams through your skin and uses sensors to measure various metrics. It then combines this data with your activity and movement, tracked by an accelerometer, to give you three daily scores: Sleep, Activity, and Readiness. The Ultrahuman Ring Air is another lightweight option that does not require a subscription.

If you prefer not to wear a device on your wrist, you can opt for a sleep tracker that clips onto your pillow, like the Withings Sleep device, or one that sits on your bedside table, like the Muse S Headband. The Withings Sleep device collects data from underneath your mattress, while the Muse S Headband works in tandem with an app to enhance meditation and breathwork.

They can help identify sleep problems and track progress to improve sleep habits

Sleep tracking bands can help identify sleep problems and track progress to improve sleep habits. They provide tailored insights into how well you are sleeping, and many include built-in coaching to improve your sleep habits. Sleep tracking bands can monitor your heart rate, respiratory rate, blood oxygen levels, and skin temperature. They can also detect interrupted sleep, letting you know when you are tossing and turning or waking during the night. Some trackers prompt you to enter information about activities that can affect sleep, such as caffeine intake, diet, and stress levels.

The Oura Ring Gen3, for example, is a titanium, wedding-band-shaped device that uses infrared light beams and sensors to measure your respiratory rate, heart rate, heart rate variability, blood oxygen levels, and body temperature. It uses these metrics to track your sleep, and an accelerometer logs your activity and movement. The Oura Ring then synthesizes these two types of data (sleep and energy output) to give you three daily scores: Sleep, Activity, and Readiness.

The Whoop band is another popular sleep tracking band. It is a lightweight, screenless bundle of five LED sensors and four photodiodes, as well as a spinning motor. The Whoop app focuses more on performance and recovery, rather than energy and rest, and is peppered with terms such as "stress," "strain," and "impact analysis." The app also suggests that you consult a Whoop Coach (powered by AI) to learn how to improve your sleep habits.

Sleep tracking bands can be a useful tool to help identify sleep problems and track progress to improve sleep habits. They provide data and insights that can help users make informed decisions about their sleep habits and experiment with different strategies to optimize their sleep.

Frequently asked questions