Everyone’s talking about tracking your sleep. Back in 2014, the Centers for Disease Control and Prevention (CDC) labeled sleep deprivation an epidemic. They found that many Americans were getting much less sleep than they needed, which contributed to numerous health and behavior issues such as falling asleep during the day, making more mistakes at work, and an increased likelihood of cardiovascular disease and other chronic conditions.
“Not getting enough sleep is linked with many chronic diseases and conditions — such as type 2 diabetes, heart disease, obesity, and depression — that threaten our nation’s health,” the CDC website explains.
As public awareness about sleep health grew, more people became interested in tracking their sleep habits. A number of sleep trackers —or devices that gather data about your sleep — are available for consumers to purchase. There are also plenty of sleep apps, which people download onto their smartphone, that can help tell them know when to go to bed and when to wake up and track some sleep data as well.
How do sleep trackers and sleep apps work? And are they actually reliable?
According to Northwestern Medicine, here’s what sleep trackers can and can’t do:
- They can measure your movement while you sleep. They do this using a device called an accelerometer, which senses any body movements you make. Smartphones and wearable trackers can both contain accelerometers.
- They can measure your sleep habits (in the most basic sense). A tracker can tell you more or less when you went to sleep and when you got up. Dr. Phyllis Zee, MD, director of Northwestern Memorial Hospital Sleep Disorders Center, said on Northwestern Medicine’s site: “Just like activity trackers, a sleep tracker can help promote a healthier lifestyle. It gives you a visual for how well you adhere to your sleep and activity goals, and helps you to be more self-aware.”
- They can’t accurately track your sleep stages. In order to truly track what sleep stage you are in, and the transitions between stages, you need information about your brain wave activity. This can only be gathered using medical equipment, which can be found in a sleep lab.
- They can’t accurately diagnose any sleep disorders. Again, accurately diagnosing a sleep disorder requires a lot of information, including brain wave activity, breathing, heart rate, and more. In order to diagnose or rule out a sleep disorder, you should consult a medical professional, who will either diagnose you based on a physical exam or ask you to spend a night in a sleep lab to collect further data.
- They can maybe tell when you are awake or asleep, depending on the tracker. “Most trackers can estimate when a person is awake or asleep,” Northwestern Medicine explains. “However, there is a degree of error. Each sleep tracker has a different degree of sensitivity to your movements, and even the algorithms can greatly affect the accuracy of the data collected. The slightest movement by your spouse or even a pet could move the device, too.”
How long have sleep trackers been around?
People have been tracking their sleep for centuries simply by noting when they went to bed and when they woke up — the old fashioned way. But personalized sleep technology did not become mainstream until fairly recently, when smartphones and wearable activity and fitness trackers hit the scene. Smartphones became mainstream in the late 2000s and early 2010s, and wearable activity monitors also became mainstream around that same time.
A paper published in 2012 looked at different types of sleep-tracking devices for the home, including shirts, headbands, and wearable wristbands (1). It concluded that there were many options on the market, but that research into these devices — and validation of their data — was necessary.
Even though sleep tracking technology has developed very fast in recent years, it’s still not a perfect science. Consumer sleep trackers are no replacement for specialized, medical sleep tracking that takes place in labs (more on that later).
Types of Sleep Trackers
There are two main types of sleep trackers: wearables, which people wear, and non-wearables or contactless devices, which are standalone (meaning people don’t wear them). Here’s a quick overview of these two types of sleep trackers, how they work, and the similarities and differences between the two.
Wearable sleep trackers
Many wearable fitness trackers also have a sleep tracking component, or people can get dedicated, wearable sleep trackers. A wearable sleep tracker is a tracker that people wear on their body, typically on their wrist like a watch. There are also some wearables that people clip to their clothing or wear as a necklace or ring.
Wearable trackers typically work by using actigraphy, which Dr. Brandon Peters described in an article as “the continuous measurement of activity or movement with the use of a small device called an actigraph.” The actigraph typically uses one or more accelerometers — that’s a device that measures acceleration — to track movement. “This information is then used to create a graph. Active times result in a peak (or bar) on the graph while quiet times, such as sleep, will be represented by a flat line,” Peters explained. Generally, wearable sleep trackers can provide the following information with some accuracy:
- A general sense of how much sleep you are getting each night, based on when you go to bed and wake up
- Whether or not you move around a lot while you are asleep
There are a ton of smartwatches, fitness trackers, and sleep trackers that come in wearable form. Common wearable sleep tracker brands include Apple Watch, Fitbit, Jawbone, Misfit, Up, Polar, Withings.
- Many wearable sleep trackers are also fitness trackers, meaning they can track your daily steps (using a pedometer) and sometimes your heart rate, the number of stairs climbed, altitude gained (during hikes, for example) and calories burned.
- Because you are wearing the device on your person, it’s unlikely that a partner or pet will accidentally move the device and alter the results.
- Some people may find it uncomfortable to sleep with a watch or tracker on their person.
- If you have a fitness tracker that you also use to track sleep, you may struggle to find the right time to recharge it since you want to track your activity during the day and at night. Finding a tracker that charges quickly can be important.
Non-wearable sleep trackers, also sometimes called “contactless” sleep trackers
There are also sleep tracking devices that you don’t wear or that don’t have to touch you at all. Some contactless sleep trackers need to be in bed with you, under your mattress or sheets. Other contactless sleep trackers simply need to be near your bed, such as on your bedside table.
Depending on the device, contactless sleep trackers work in a variety of ways. Here are some examples:
- The Zeeq Smart Pillow is — you guessed it — a pillow with sleep tracking technology. Inside the memory foam pillow, there are microphones, speakers, vibration monitors, a gyroscope, and an accelerometer. The pillow uses these components to stream music wirelessly, track and analyze your sleep, and detect snoring. It has a battery life of about two weeks.
- Eight, a smart mattress cover, collects data including room temperature, light levels, and background noise. It also has sensors to track your heart rate, breathing, and movement.
- SleepScore Max, a standalone monitor, uses a proprietary SleepScore technology, based on something like radio waves, to measure your sleep.
- Contactless sleep trackers won’t feel uncomfortable on your body, making them ideal for people who don’t want to wear a smartwatch or other wearable while they sleep.
- A contactless sleep tracker may not be able to accurately measure your heart rate or breathing, since it is not necessarily close to your body.
- They may be less accurate for people who sleep with a partner or who share a bed with their pets.
Types of Sleep Apps
There are two main types of sleep apps: apps that pair with wearable trackers or standalone trackers, and apps that simply use the data from your smartphone to track your sleep.
Apps that pair with other technology basically “translate” data for you. For example, let’s say you have an Apple Watch or a SleepScore Max. The companion apps for these devices make it easy for you to look at the data they gather and view patterns over time. Standalone apps, which don’t require buying pricey equipment, make the most of the existing hardware in your smartphone to provide information about your sleep. They don’t need to be paired with outside devices, meaning the overall cost is much lower. However, they can’t measure data like your heartbeat, and their ability to measure your movement may be limited as well.
Things to Consider Before Buying A Sleep Tracker
Before you purchase a sleep tracker, there are a few things you should consider. Here are some of the factors you should bear in mind, from budget to your ultimate goal and more.
Firstly, why do you want a sleep tracker?
Do you feel like you sleep really badly or really well and want to see if your hunch is true? Are you just interested in gathering more data about yourself? Would you like to sleep more than you do currently, or less? What appeals to you about tracking your sleep in the first place?
What’s the current state of your sleep?
Obviously, it’s hard to tell objectively how much sleep you are getting without sleep tracking data. But you may have a general sense of how much you are sleeping based on your bedtime and what time you wake up, and your energy levels during the day can suggest whether you are getting enough sleep or whether you are actually sleep deprived and could use more rest.
What is your current sleep situation?
Do you share a bed with a partner and/or pets? Are you in a college dorm or another setting with multiple other people? If you don’t sleep alone, a wearable sleep tracker might make the most sense, so movement and noise from others in your bedroom doesn’t interfere with the data. If you sleep solo, you might look into standalone trackers. (Some standalone trackers claim to work for couples.)
Do you have a smartphone? If so, what type?
The vast majority of sleep trackers are designed to sync with your smartphone, meaning it may not make sense for you to get a sleep tracker if you prefer not to have a smartphone. Many trackers will work with both iPhone and Android models, but some only work with one or the other. Research what’s compatible with your phone and how much you like the look of various apps.
What’s your budget?
The budget you are working with can help determine which sleep tracker will make the most sense for you. Consider that you might not actually enjoy tracking your sleep or find the data useful, so some people aren’t willing to spend a lot of money on wearable or contactless sleep trackers in case they don’t end up using them.
If you are looking for the most affordable option: You may want to start by buying an app that uses your smartphone’s existing technology to track your sleep. These apps range from free to about $30/year. Some popular sleep apps include SleepCycle, Pillow, Sleeptracker 24/7, and Sleep As Android.
If you’d like a wearable device that you can use for fitness and activity tracking as well as sleep tracking: Prices start at around $100 for a basic Fitbit and go up to $300+ for some Garmin and Apple Watch models.
Research which type of wearable is best for you based on your needs: For instance, how active are you? Do you want something with a heart rate monitor? Would you prefer something waterproof?
If you want a standalone sleep tracker: Prices begin around $40 for an extremely basic model and go higher depending on the brand.
Why Sleep Trackers/Apps Should Not Replace a Doctor’s Visit
Because sleep trackers and apps aren’t medical diagnostic tools, they should never replace a doctor’s visit. If you are worried that you might have a sleep disorder or another health issue, go to a medical professional directly to explain your concerns and discuss any symptoms. If your sleep tracker info suggests an issue, you can mention it — but know that trackers are not a reliable replacement for diagnostic tests.
In May 2018, the American Academy of Sleep Medicine (AASM) released an important position statement about sleep tracker data in the Journal of Clinical Sleep Medicine. The gist: More and more people are collecting their sleep data using trackers and apps and wondering if their data shows signs of a health problem, but the information isn’t yet accurate enough for doctors to draw reliable conclusions from it. The statement notes that sleep tracker wearables and apps are usually sold to consumers as lifestyle items, that the data they collect has rarely been validated, and that very few sleep trackers have been reviewed by the Food and Drug Administration (FDA).
In a press release, Dr. Seema Khosla, medical director at the North Dakota Center for Sleep, said that she saw increasing numbers of patients seeking medical assistance for their sleep based on data collected using consumer sleep tracking technology. Dr. Khosla called for more guidance on using consumer sleep trackers in clinical practice and for suggestions on how to talk to patients about what their sleep trackers can and cannot accurately tell them.
“Given the heightened public awareness of the importance of sleep, and of diagnosing and treating sleep disorders, I believe we will continue to see more patient-generated health data,” she said. “We need some guidance both for how to utilize consumer sleep technology in our practice and also how to communicate with our patients about the specific metrics their devices are measuring.”
The bottom line, according to AASM president Dr. Ilene Rosen, is that “consumer sleep devices currently are unable to diagnose sleep disorders.”
That means you should always consult a medical professional if you think you have a sleep problem, rather than trying to diagnose yourself and fix an issue on your own. In order to diagnose sleep issues, your doctor might recommend you undergo a sleep study.
So What Happens During a Sleep Study in a Lab?
A sleep study, also known as a polysomnogram, is a diagnostic tool that doctors use to monitor your sleep and look for signs of a sleep disorder or related health issue. According to the Mayo Clinic, your doctor may recommend a sleep study if they think you might have any of the following conditions:
- Sleep apnea, a condition where your breathing stops and starts while you are asleep
- Periodic limb movement disorder/restless legs syndrome
- Narcolepsy, a condition that causes “sudden attacks of sleep”
- REM sleep behavior disorder, where you act out your dreams while you are asleep
- Unusual behaviors during sleep
- Unexplained chronic insomniaSleep studies are typically non-invasive and painless. Basically, as the Mayo Clinic explains, you spend the night in a sleep lab where various machines monitor your “ brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements during the study.”
To prepare for the study, you may be advised not to consume alcohol or caffeine and to avoid napping during the day of the test. Typically, you’ll arrive for the sleep study — which will be held at a hospital or in a sleep lab — shortly before your normal bedtime. There, technicians will help set up the equipment.
According to the Alaska Sleep Clinic, the monitoring equipment used during a polysomnogram includes:
- EEG (electroencephalography) electrodes, for measuring electrical brain activity (these help determine what stage of sleep you are in, using your brain wave patterns)
- EOG (electrooculography) electrodes, which measure eye movement
- EMG (electromyography) electrodes, which measure muscle activity
- EKG/ECG (electrocardiography) electrodes, which measure the electrical activity in your heart
- Belts around your chest and diaphragm to measure breathing
- A nasal cannula, which measures inhalation and exhalation
- A pulse oximeter, which measures blood oxygen levels
“Approximately two hours before bedtime a sleep technologist places electrodes on your head and body,” the Ohio Sleep Medicine Institute explains. “Each one is installed using a special jelly and checked with a meter for appropriate functioning. An elastic band around the waist and heat-sensitive wires in the nose and mouth are positioned to monitor your breathing. A probe in a finger is installed to measure the level of your blood oxygen. Your bedroom is in direct contact through an intercom system with the diagnostic unit system where the sleep technologist monitors your recording overnight.”
While you sleep, the sensors collect data on the following:
- Brain wave activity
- Eye movements
- Heart rate
- Blood oxygen levels
- The position of your body
- Movements of your stomach and chest
- Movements of your limbs
- Snoring (and other noises such as talking in your sleep)
Someone will monitor you throughout the night. In the morning, you’ll wake up and be free to go. According to the Alaska Sleep Clinic, some people struggle to get a full night’s sleep in the lab — but most patients sleep more than they think they do. What’s more, your technicians were likely able to collect the data they needed even if you didn’t sleep all night.
How to Care For Your Sleep Tracker
A wearable or standalone sleep tracker will typically come with detailed instructions on how to care for the device and what you should avoid doing in order to keep the device in good shape. Some general rules of thumb to follow:
- Keep your tracker away from water unless it is specifically designed to be waterproof
- Regularly charge any trackers that run on a battery
- Update software as needed
So, Are Sleep Trackers Worth It?
Ultimately, it depends.
If you plan on tracking your daily activity anyway and would love some general data on how much sleep you are getting, it may well be worth investing in a wearable activity tracker. If you’re interested in your sleep data and understand the limitations of consumer technology, there’s no reason why you shouldn’t look into contactless sleep trackers.
But if you are worried that you have a sleep disorder, you should definitely seek a medical opinion rather than relying on at-home sleep trackers.
To learn more about what sleep trackers can and can’t do, and for details about how they work, check out the following resources:
- Do Sleep Trackers Really Work? — Johns Hopkins Medicine
- What Sleep Trackers Track — Northwestern Medicine
- What Happens In A Sleep Study? — Johns Hopkins Medicine
[Editor’s Note: The content provided on this site is for general informational purposes only. Any information provided is not a substitute for professional medical advice. We encourage you to consult with the appropriate health expert if you have concerns.]
Featured image: Andrey_Popov/Shutterstock
- Kelly, Jessica M., et al. “Recent Developments in Home Sleep-Monitoring Devices.” ISRN Neurology, vol. 2012, 2012, pp. 1–10., doi:10.5402/2012/768794.