Sleep-related problems have become commonplace in modern society, with over 35% of American adults sleeping less than the recommended seven hours per night and almost half reporting feeling sleepy between three and seven days per week [1].
In an effort to address this problematic relationship with slumber, our obsession with tracking sleep has grown considerably in recent years. It is estimated that one in three people use a wearable sleep tracker to objectively measure how much shut-eye they’re getting each night.
Accordingly, there’s been a huge surge in brands introducing personal sleep-tracking devices to capitalize on this obsession, from wristwatches and rings to bedside motion sensors and devices that clip to your pillow.
Once upon a time, the only way to accurately monitor your sleeping patterns was by being wired up to a high-tech machine in a sleep lab with qualified experts to interpret the sophisticated data. Nowadays, you can do it yourself easily and unobtrusively in the comfort of your own home.
But before we take a look at how these devices work, let us introduce you to Pzizz. This effective sleep app uses clinically-validated techniques and patented technology to bring you beautiful ‘Dreamscapes,’ immersing you into a state of deep relaxation to help you gently slip into deep, restorative sleep. Download Pzizz on the App Store or Google Play to enjoy your free trial today.
So you’re probably wondering, how do sleep trackers actually work? Can the data be trusted? And how effective are they in improving sleep quality? Keep reading to discover answers to these pressing questions and more.
There are two different types of sleep trackers: wearable and non-wearable devices. Wearable trackers are available as headbands, wristwatches, bracelets, rings, or chest straps. Non-wearable trackers come in the form of phone apps and other bedside devices or ones that you place under your bedsheet or pillow.
While sleep trackers come in many forms, the technology is all designed to do one thing: track your sleep quality by measuring variables such as your length and depth of sleep as well as any disturbances throughout the night. Moreover, some devices claim to track your various sleep phases and wake you up at the optimum point of your sleep cycle to avoid grogginess upon waking.
Based on this feedback, such devices can provide valuable insight into how much quality sleep you’re getting each night and empower you to implement the environment and lifestyle changes necessary for achieving a good night’s sleep.
There are several ways sleep measuring tools track sleep; the exact mechanism depends on the specific device you’re using. The most common sleep parameters include:
Small motion detectors (known as accelerometers) track your amount of movement throughout the night to measure sleep quality and quantity. Once the tracker detects that you have been inactive for a certain length of time or only detects movement indicative of sleep (such as rolling over), it assumes that you’re asleep.
Variations in heart rate and breathing patterns are closely associated with different stages of sleep – with rates dipping once you enter deeper stages of sleep.
With this data, tracking devices can calculate when you enter REM, light, deep sleep stages, and any interruptions during the night. Based on this information, some devices time your alarm to sound when you’re in the lightest stage of sleep to help you wake up easily.
Using photoplethysmography (PPG) technology, certain devices emit red and green light to detect heart rate. Blood underneath the skin reflects the red light and absorbs the green light. Each heartbeat allows for more of the green light to be absorbed, while less is absorbed in between each heartbeat.
Additionally, some wearable devices use pulse oximetry consisting of red and infrared sensors to detect levels of oxygen in the blood to accurately measure respiration rates, while non-wearables use radio frequency technology. Respiration patterns are especially important in identifying disturbances caused by sleep disorders, such as snoring and sleep apnea.
Your body’s core temperature also fluctuates as you sleep; for instance, non-REM sleep is accompanied by core and brain cooling. Accordingly, certain wearable devices monitor skin temperature in the same way as a thermometer to detect sleep onset and transitions into different sleep phases.
Some sleep tracking devices use microphones, sensors, and thermometers to measure light and noise levels and room temperature and humidity to measure sleep quality and duration.
Certain sleep trackers prompt you to input information about your habits and behaviors throughout the day to establish how they may affect your sleep quality. For example, stress levels, when and how much caffeine or alcohol you’ve consumed, the amount of physical activity, and when you had your last meal as these can all impact how much or little you sleep at night.
Most trackers on the market will gather all this feedback and produce a report that provides insight into your sleep quality. This allows you to track changes over time, set goals, and receive advice on any changes you can make to optimize your sleep experience.
Their popularity may have surged in recent years, but evidence of the accuracy of sleep trackers remains scarce. However, one study has analyzed the effectiveness of sleep trackers compared to polysomnography tests (a test performed in a specialist sleep lab by qualified experts).
Research indicates that when compared to such tests, sleep trackers are only 78% accurate in identifying sleep versus wakefulness. Moreover, this figure dropped to 38% when measuring how long it takes for a person to fall asleep [2].
This evidence suggests that sleep trackers cannot measure sleep directly. Instead, they measure inactivity to estimate when a person has fallen asleep and for how long. Using movement (or lack thereof) as a marker to measure sleep has limitations, as many people tend to move frequently throughout their sleep.
Furthermore, sleep trackers may be unreliable in differentiating sleep from wakefulness in those with insomnia, especially those who remain extremely still in bed trying to fall asleep. As a result, devices may overestimate total sleep time and underestimate the time taken to fall asleep.
On the upside, technology is improving, and more sophisticated devices incorporating heart rate and respiration data may be more accurate in measuring sleep duration and quality, particularly for people with sleep disorders.
While many new models of sleep tracking devices claim to identify different sleep stages using a range of biomarkers, they provide a guesstimate at best. Unfortunately, this means they cannot be considered scientifically accurate. The only way to gather precise data about the sleep cycle is by monitoring brain wave activity – a metric current sleep tracking devices aren’t advanced enough to measure.
It’s a given that a polysomnography test will return more accurate results due to its comprehensive analysis. This gold standard of sleep assessment is conducted using state-of-the-art technology to measure a whole host of parameters, including brain wave activity, blood oxygen levels, and eye movement.
Furthermore, specialists who conduct such tests have the knowledge and expertise to accurately translate the data and provide meaningful feedback. The average layperson is unlikely to be able to understand how to interpret the data from their devices.
Studies have also shown how sleep trackers can induce a placebo effect in users, whereby their symptoms and perceptions are influenced by how they expect to feel. Subsequently, such devices could be a possible cause of sleep-related stress and anxiety, proving counterproductive.
For example, one study examining perceived sleep quality involved participants being given sham sleep trackers and false information about their sleep. Participants who were told they had a better night’s sleep exhibited elevated alertness, mood, and wakefulness than those who were told they slept badly, even though both groups slept for the same time [3].
Measuring sleep quality is a highly-individualistic process that cannot be done with a one-size-fits-all approach. However, all sleep-tracking devices must follow a set algorithm when providing data on sleep, regardless of its distinct nature. Consequently, assumptions made by these devices may not necessarily be scientifically-accurate and won’t be as effective as seeking professional help.
Despite the downsides, sleep trackers are an affordable and useful way of assessing sleep. Whereas being hooked up to a machine in a laboratory can feel unnatural and uncomfortable (ultimately preventing you from sleeping normally), sleep tracking devices allow you to track your sleep in a natural and familiar environment. People can also measure trends in their sleeping habits over a longer period of time rather than spending one or two nights in a clinical setting.
It’s important to note that tracking your sleep doesn’t automatically improve your sleep quality. The key is using the information sleep trackers provide to identify patterns and improve sleeping habits.
For instance, you may experience restless nights when drinking alcohol after 8 pm. Or perhaps you feel groggy in the mornings when sleeping from 10 pm to 6 am, while sleeping from 11 pm to 7 am gives you more energy. You may also discover that doing 30 minutes of cardio in the afternoon gives you a better night’s sleep.
Such data can provide meaningful insights, prompting you to make necessary lifestyle changes and implement new habits that optimize your sleep experience. Moreover, many sleep apps offer detailed reports you can share and discuss with your doctor to help determine whether you require clinical testing.
Whether or not you decide to track your sleep, remember doing so won’t actually improve your sleep experience. Instead, why not use the Pzizz app to sleep well each night?
Pzizz has already helped millions of people overcome their sleep troubles with its clinically-tested techniques and patented technology. The app is designed to quieten your mind, helping you to fall asleep fast, stay asleep throughout the night and wake up feeling refreshed.
The app’s creators have taken advantage of the most up-to-date clinical research to devise ‘dreamscapes’-a blend of music, voiceovers, and sound effects-designed to invoke deep relaxation and rest and proven to help you sleep better.
Unlike sleep tracking apps, Pzizz doesn’t overwhelm you with extensive data that are often difficult to make sense of. Instead, all you need to do is set the time you want to wake up and leave the rest to Pzizz.
With highly-customizable features, including adjustable narrations, volumes, and more, you can tailor your listening experience to your distinct sleep needs. With over one billion different audio pieces to choose from, it’s safe to say you won’t get bored by the same repetitive playlist.
So if poor-quality sleep is taking a toll on your life, it’s time you joined over a million people who have already put their sleep woes to bed with Pzizz. Enjoy your free trial by downloading Pzizz on the App Store or Google Play.
Whether you’re using a wearable or non-wearable sleep tracker, such devices collect data on various biometrics, including heart rate, breathing, and movement, to determine when you’re asleep and, in some cases, detect which stage of sleep you’re in. Once the device detects lowered heart and breathing rates and no movement for a period of time, it assumes you’re asleep.
Although tracking your sleep is a good start to monitoring how much quality rest you get each night, you might want to take such information with a pinch of salt as the data isn’t always 100% accurate. Moreover, sleep trackers alone won’t improve your sleep; the key is to use the data to implement healthy habits that improve your sleep and overall quality of life.
As useful as sleep trackers can be in providing insights into sleep quality and duration, they can exacerbate sleep-related stress and anxiety, in turn worsening symptoms of insomnia. If you’re already prone to worrying or anxious thoughts, then it may be best to use sleep-tracking apps with caution, as they can cause you to fixate on how much sleep you’re getting, which can worsen sleep quality.