The U.S. Department of Health and Human Services defines Sleep Apnea as a disorder characterized by disruptions in breathing such as pauses or periods of shallow breathing while sleeping. These disruptions may last for as long as a few minutes and can occur many times, typically after loud snoring. People with Sleep Apnea often feel sleepy or tired during the day, and it may also cause hyperactivity in children. Wearable devices like FitBit and Apple watches are being used as sleep trackers with increasing frequency. But, do they actually work?
A wearable device, or wearable, is an electronic device with a microcontroller that can be worn directly on the body or incorporated into clothing. They often have internet connectivity, making them part of the Internet of Things (IoT). The cost of wearable technology dropped to a level that would allow widespread adoption by 2009, and sales began growing rapidly by 2013.
Smartwatches and activity trackers are some of the best-known examples of wearables in consumer electronics. Wearables can collect biometric data to provide valuable information on the heart, brain, and muscles. They also have great potential for generating big data, so researchers are shifting their focus to the development of algorithms that will provide insight into the collected data.
The reference standard for the diagnosis of Sleep Apnea remains cardiorespiratory polysomnography, which is a multi-parametric sleep study of heart and lung functions. However, the testing capabilities of HSAT (Home Sleep Apnea Testing) devices have been getting more accurate and specific to Sleep Apnea. The SCOPER scheme has been developed to evaluate and categorize HSAT systems by validating the most important functions for diagnosing Sleep Apnea.
This acronym indicates these functions as follows:
- Sleep (S)
- Cardiovascular system (C)
- Oxygen saturation (O)
- Body position (P)
- Respiratory effort (E)
- Airflow (R)
The SCOPER process checks the functions needed to characterize Sleep Apnea rather than simply merely counting individual apnea events. For example, it evaluates an HSAT’s ability to distinguish between central and obstructive apnea, which is vital for developing an effective treatment plan. This evaluation scheme thus allows new sensors and software to meet the criteria for a successful diagnosis of Sleep Apnea. HSAT systems also need to evaluate the severity of the Sleep Apnea when reporting measurements.
As always, it is recommended to check with your doctor to discuss a diagnosis and treatment plan for Sleep Apnea if you suspect you may have symptoms. While home sleep tests are growing in popularity, your doctor may still order a sleep study in a sleep lab for more extensive testing.
The most popular wearables used as sleep apnea detection devices include products from Garmin, Fitbit and Apple.
How Do SmartWatches Track Sleep?
How does your Apple Watch, Fitbit, or Garmin know when you’re asleep? Well, actually, it doesn’t. These devices actually make an educated guess.
Most wearables estimate sleep using a tiny device called an accelerometer, which tracks movement. The sleep app then compares how you’re moving with data about how people typically move in their sleep. A complex algorithm then uses this information to make an estimate of your sleep duration, sleep phases, and sleep quality.
This process is called “actigraphy” and it’s actually used by healthcare providers, sleep researchers, and even NASA. But by itself, actigraphy has a hard time telling the difference between sleeping and wakefulness, and can easily be fooled by people who stay very still.
For example, one study found that wrist actigraphy overestimated total sleep time by over 22 minutes.
So what about the devices that also track heart rhythm, blood oxygen levels, and even respiratory rate? Are they more accurate at tracking sleep and, more importantly, can they detect sleep apnea? Let’s take a look at some of the different devices.
Can the Fitbit Detect Sleep Apnea?
Newer models of the Fitbit report on almost all of the health data signals used to detect sleep disorders, but they cannot combine that data to diagnose sleep apnea. And it’s designed that way on purpose: The Fitbit is considered a “wellness device” and not a medical device, so it is not regulated by the FDA. This means the Fitbit cannot claim to detect, diagnose, treat, or prevent any diseases or conditions.
This is the reason why Fitbit users can receive a report on variations in their blood oxygen levels (SpO2), but not the actual readings of those changes.
If the makers of Fitbit wanted to be able to detect sleep apnea they would have to undergo rigorous and expensive clinical trials to seek FDA approval.
Still, the Fitbit’s built-in pulse oximeter and accelerometer can provide wearers with valuable data. You should talk to your doctor about any changes to your heart rate, respiratory rate, blood oxygen, sleep quality, or if you frequently wake up during the night. These could be indications of OSA, or another serious health condition.
Can the Apple Watch Detect Sleep Apnea?
Unlike the Fitbit, the Apple Watch contains a heart-rate sensor that is actually considered a Class II medical device. Combine that with third-party health apps, and the Apple Watch may potentially be able to detect (but not diagnose) sleep apnea.
Like with other smartwatches, the blood oxygen sensor on the Apple Watch is considered a “wellness device” and not allowed to claim to detect or diagnose any health conditions. However, Apple went through the process of getting FDA clearance for the ECG features on Apple Watch Series 6 and 7.
With this heart-rate sensor, a watch app called Cardiogram claims to be able to detect atrial fibrillation, hypertension, and even sleep apnea. The Cardiogram app uses an advanced AI called DeepHeart to analyze your heart rhythm, ECG, and activity data. It can then report on your cardiovascular health with 82 percent accuracy compared to other wearables by themselves.
It’s important to note the difference between detection and diagnosis, however. While Cardiogram can detect the likeliness of sleep apnea, it cannot be used to diagnose OSA.
What Happens if Sleep Apnea is Detected?
Currently, even the most advanced smartwatches and fitness trackers can only detect the possibility of sleep apnea, and recommended that you seek a further diagnosis. Only a sleep study analyzed by a board-certified clinician can diagnose obstructive sleep apnea.
Wearable devices may overestimate sleep time and sleep efficiency when compared to the more sophisticated technologies available in a sleep lab. However, sleep measurements from a wristband may be a good starting point for a discussion with a doctor about sleep. If a doctor suspects a sleep disorder, formal sleep testing using a sleep study may be ordered.
Luckily, advances in technology mean you can have a sleep study performed at home or in a sleep lab.
If the sleep study finds that you do have OSA, your doctor will likely prescribe CPAP therapy. A CPAP machine is a non-invasive treatment that uses pressurized air to prevent your airways from collapsing during sleep.
If you suspect that you or a loved one may have sleep apnea, talk to your doctor about scheduling a sleep study right away. Then reach out to Alaska Sleep Clinic! All of our labs in Anchorage, Fairbanks, Soldotna and Wasilla are accredited with the American Academy of Sleep Medicine (AASM) and our medical directors are all board-certified and Fellows with the AASM. Call us today @ 907-770-9104 or go to our website, www.alaskasleep.com . Improve Your Sleep. Improve Your Life.
