Smartphones: Tracking Your Sleep And Pulse?

Sleep and heart rate tracking have become increasingly popular in recent years, with many consumers turning to wellness technology to monitor their sleep patterns and heart rate. This has led to the development of various smartphone applications that can track sleep and heart rate through in-built smartphone features such as speakers, microphones, and cameras. Sleep tracking applications use technologies such as sonar to measure body movement and breathing rate, while heart rate tracking applications use optical detection to find an individual's pulse rate by illuminating the blood vessels under the skin. This article will explore the capabilities of these applications and the methods they employ to track sleep and heart rate.

Optical detection methods to track pulse rate

There are several optical detection methods to track pulse rate. These methods can be used by various devices, including smartphones, and some are more accurate than others.

One optical detection method is to use a smartphone's rear camera to estimate beats per minute. This is done by detecting colour changes in a person's fingertip, which indicate the pumping of blood through the capillaries. This method is available on Google Fit for Android and iOS.

Smart rings are another device that can use optical detection to track pulse rate. These devices are worn on the finger and use optical detection to track heart rate and other vital signs. Pulse oximeters are similar devices that also use optical detection to track pulse rate and blood oxygen levels. They are often used in hospitals but are also available for personal use.

Optical sensors for heart rate monitors, such as those developed by ROHM, use a photoelectric pulse wave method. This involves emitting red or infrared light from the body surface and detecting changes in blood flow during heartbeats by measuring the amount of light transmitted through the body. This method is limited to areas where light can easily penetrate, such as the fingertip or earlobe.

Another optical detection method is to use reflection-type pulse sensors, which emit infrared, red, or green light towards the body and measure the amount of light reflected using a photodiode or phototransistor. By sensing the blood flow rate and changes in blood vessel volume during heart contractions, these sensors can measure the pulse wave signal.

In-ear optical heart rate monitors (HRMs) are also available and tend to be more accurate than wrist-based ones because the ear doesn't move as much, and the skin of the ear works better for optical readings. These devices use optical technology to send light into the skin and read the reflections. The data is then translated into a pulse measurement based on how light scatters when it hits the blood.

Heart rate monitoring via smartphone apps

Your smartphone can now monitor your heart rate, sleep patterns, and sleep quality. This is usually done through a smartphone app that uses your phone's camera to measure your heart rate. The app detects changes in blood volume under the skin's surface, a practice called photoplethysmography. The flash of your phone's camera illuminates the skin and creates a reflection to capture the ebb and flow of blood. This is based on the fact that blood absorbs light, and the amount of blood reaching the capillaries in your fingers and face swells and then recedes with every heartbeat.

There are many heart rate monitoring apps available for smartphones and wearables. Some of the most popular ones include Cardiio, which is free to use and can measure your heart rate in under 15 seconds. It also has a built-in alert to remind you to take your pulse, which can be set to daily, weekly, or monthly. Cardiio also offers a free circuit workout and the ability to export your data. Additional features can be purchased piecemeal or through a one-time upgrade to pro for $9.99. Another popular app is Instant Heart Rate, which is free and can measure your heart rate in less than 10 seconds. It also has a "stress test" feature and can be used to monitor irregularities in your heart rate. Kardia is another unique fitness app that brings expert heart health guidance to your smartphone. It offers free and paid plans, with the paid version giving you access to an ECG review by cardiac physiologists every 90 days. Welltory is another app that offers personalized guidance and inclusive healthcare management. It is available for both iPhone and Android and provides detailed data analysis.

While these apps are convenient and can provide useful information, they are not as accurate as medical equipment and should be used for informational purposes only. For example, when researchers compared four popular apps to clinical measurements, they found that the heart rate readings generated by the apps were off by over 20 beats per minute in more than 20% of measurements. Therefore, it is important to take app readings with a grain of salt and consult a medical professional if you have any concerns about your heart rate or sleep patterns.

Sleep tracking using sonar technology

Sleep tracking has become increasingly popular with consumers, and there are now many choices available. Traditionally, sleep tracking was only possible in a sleep laboratory or as part of a research study, but advancements in technology have allowed users to accurately view their nightly sleep patterns from the comfort of their own homes.

Sleep.com has developed an app that uses sonar technology to track sleep. The app sends out silent, inaudible sound waves through a smartphone's speakers, which reflect off the user's body and are picked up by the phone's microphone. The app's advanced algorithms then interpret the shape and movement of these sound waves to measure the user's breathing rate and body movement, tracking their sleep patterns throughout the night. This includes measuring sleep duration, the time it takes to fall asleep, light sleep, deep sleep, REM sleep, and wake time.

Sonar technology has been proven to accurately gauge distance and spaces, and this capability is leveraged to measure body movement during sleep. The sound waves emitted by the app are within the range considered safe, as they are transferred through the air and are not applied directly to the body, emitting minimal energy.

The Sleep.com app provides insights and recommendations to guide better sleep based on the tracked data. It offers a free version that tracks seven days of sleep, while a subscription for $4 a month keeps a complete sleep history and formats records to send to a doctor.

Wearable sleep trackers

There are various types of wearable sleep trackers available in the market, including rings, watches, and fitness trackers. Some popular options include the Oura Ring, Whoop, Fitbit, Apple Watch, and Garmin. These devices use direct skin contact to measure your heart rate and motion, providing insights into your sleep and wake patterns. They can also track sleep duration, sleep quality, and sleep phases, helping you understand your sleep habits and make adjustments for better rest.

It is important to note that the accuracy of wearable sleep trackers may vary. Some trackers rely on actigraphy, which measures movement, and may not always distinguish between sleep and wakefulness accurately. For example, they may assume you are sleeping when you are lying still awake. To obtain medically accurate sleep data, a polysomnography test or a medical sleep study is recommended.

Some sleep trackers also have additional features such as guided meditations, breathing exercises, bedtime stories, daily sleep journals, and coaching. These features can enhance the overall sleep experience and provide users with tools to improve their sleep hygiene and overall well-being. Additionally, some trackers can integrate data from the previous day's activities and the previous night's sleep to make more personalised recommendations, such as suggesting rest after an intense workout.

Sleep quality and patterns

Sleep tracking devices can help you recognize patterns in your sleep habits. They can help you answer questions like: Do you feel more sluggish when you sleep from 10 p.m. to 6 a.m. but more energetic when you sleep from 11 p.m. to 7 a.m.? Do you sleep better when your bedroom is cooler or on days you exercise? Is your sleep disrupted if you have caffeine after lunchtime?

There are a variety of sleep trackers available in the market. Some are below-mattress sensors, which gauge movement to determine when you’re asleep. Others are wearables that you can strap to your wrist, like those made by Fitbit, Whoop, Apple, and Oura. These use direct skin contact to discern your heart rate and motion, getting a sense of your sleep and wake patterns accordingly.

If you don't want to wear a watch or a fitness band to bed, there are also apps that can track your sleep using your phone. These include Sleep as Android, Sleep Cycle, SleepScore, and Pillow. Sleep as Android can help you fall asleep with the sounds of nature, identify the best time to wake you up gently, record your snoring and sleep talking, and connect to a host of third-party apps and devices. Sleep Cycle can be linked to other information about your sleep patterns, like coffee consumption and exercise. SleepScore uses your phone's microphone and speaker to judge how well you're sleeping, covering how long it takes you to fall asleep, and the time spent in light, deep, and REM sleep. Pillow works with an Apple Watch or an iPhone placed on the bed, analyzing your movements to record how long you've been sleeping and splitting your sleep into light, deep, and REM sleep.

For exact data about your sleep habits, you would need to do a medical sleep study, which monitors brain waves to analyze the stages of sleep you cycle through during the night. Such studies are helpful for diagnosing conditions like sleep apnea and other sleep disorders.

Frequently asked questions