Why Use A Sleep Tracker:

To get a good night's sleep and wake up feeling well-rested and ready, the average adult needs 7-9 hours of sleep. But according to the CDC, almost one third of all Americans chronically get less than that suggested amount of sleep. 

By definition, they are sleep deprived.

See Also: Sleep Your Weigh To Weight Loss

The reasons for this statistic are many: some people simply don't make it a habit to get to sleep on time; other people get poor-quality sleep from caffeine or blue light exposure, and some people may have underlying sleep disorders. 

This is where wearable sleep trackers can make a difference. It's estimated that 80% of all cases of sleep apnea--a huge contributor to sleep deprivation in adults--go undiagnosed.

As technology improves and people become more interested in wearable devices and fitness tracking, we can hope that sleep tracking will increase, and people will become more mindful of their sleep health. In addition to health, the market for sleep tracking devices is expected to grow as well, to almost half a billion dollars in the United States by 2024.

How Sleep Tracking Works:

When you're asleep, your body activity obviously drops. Your heart slows down, your brain becomes less active, and your muscles relax. Because most fitness trackers or smartwatches measure your heart rate or ECG, they are able to detect the drop in heart rate when you're asleep.

By recording metrics of your slower heart rate and breathing, allows standard fitness trackers to function as sleep trackers too. 

Fitness trackers functioning as sleep trackers are not perfect--there is some heart rate variability between sleep cycles--but in general, they can provide fairly reliable metrics on your sleep quality. 

Assuming a pulse below your resting heart rate is correlated with sleep time is usually accurate, and enables fitness trackers to track your sleep in real-time and provide useful data on your health. 

Accelerometers

Accelerometers are small detectors placed inside many devices; they detect a rapid change in speed or direction, like when you drop your phone or move it around, and are responsible for several tracking features. Your smartphone has them for sure.

Most running watches, fitness bands, pedometers, active wristbands, or other fitness trackers include them as well.

By measuring change in speed or direction, accelerometers can provide devices with useful data like steps taken or activity tracking. Accelerometers can also contribute to sleep tracking, but measuring extended periods

Actigraphy

Actigraphy is another word for activity tracking. Nearly all smartwatches and wearable fitness trackers are capable of connecting to iOS or Android devices through Bluetooth, and most have a companion app on your phone. The companion apps can store your fitness tracker's data, and show you trends giving you a birds-eye view of your health metrics, including resting heart rate, blood oxygen levels, sleep scores, and more. 

Other Metrics

Some smartwatches may include ambient light sensors or altimeters. The data they provide can provide metrics on your daily light exposure, activity, and time outdoors, to supplement other health data. 

Fitness Tracker Related Functions:

Heart Rate and Rhythm Tracking

Many fitness trackers have sensors that automatically check your resting heart rate at regular intervals. Some also have ECG or other heart rate monitoring sensors to provide even more data. Fluctuations in your heart rate are used to calculate other metrics like daily activity, sleep quality, and overall wellness. 

Activity Tracker

Naturally, fitness trackers serve as activity trackers. By measuring your heart rate and blood oxygen levels, they can measure the intensity of your daily activity, or effectivity of your workout.

Body Temperature 

Some newer fitness trackers may also be equipped with thermometers to detect and track your body temperature. This can be useful in a cold environment to alert you if you develop hypothermia with knowing. Athletes may also find it useful to alert themselves if their body temperature spikes too high and they need to cool down. 

Other Frequent Questions

1. Which wearables have sleep tracking?

Almost all mainstream wearables can calculate sleep time from your heart rate fluctuations. These include the Apple Watch, Fitbits, Samsung Galaxy watches, and more. 

2. How accurate are smartwatches for sleep?

As mentioned, smartwatches are not perfect. By tracking the heart rate to determine sleep quality and sleep time, some errors can be made. Some sources have found that they can over or underestimate sleep time. When viewing your sleep time in the companion app, keep in mind the actual time may be a little bit more or less.

And remember, even if one or two days report noisy data, it's the trend over a longer period of time that matters more. 

3. How much deep sleep is normal?

Deep sleep can refer to two different sleep cycles: Slow-wave sleep (SWS), and REM. Both are important. SWS is where growth hormones to repair your body's tissues are released; REM is where your brain consolidates the information its learned that day, and stores it in memory. It also performs maintenance functions by removing waste from your neurons.

It's recommended that you get about ninety minutes to two hours of REM sleep, which is the most restorative sleep stage. Without REM, you feel sleep-deprived, and your mental ability suffers until you get good-quality sleep again.

We're extremely pleased with the accuracy of the FitTrack Atria 

4. Why you should track your sleep?

Sleep is incredibly important, and sleep quality is often overlooked. As mentioned, SWS and REM are important for your brain's wellness. If they suffer, many health problems may occur, including weight gain, greater risk for heart problems, and possibly even dementia. 

Therefore, if you feel you're being sleep-deprived, or just want to develop sleep habits to improve your wellness in general, getting into sleep tracking may be a good idea.

Most wearable fitness trackers also boast the ability to monitor your sleep anyway, so why not give it a try?

5. Can fitness trackers detect sleep apnea?

Sleep apnea is a sleep disorder where you frequently wake up during sleep, sometimes as much as 100 times per night. Since you're half asleep, you don't remember it. These wake-ups are triggered by your brain not getting enough oxygen, and besides having potentially harmful side effects on your brain, they seriously disrupt your sleep quality. 

Fitness trackers may or may not be able to detect sleep apnea. One of the primary indicators for sleep apnea--and the reason you wake up--is low blood oxygen levels or low SPO2 saturation. If your fitness tracker boasts this metric, and the companion app displays repeatedly low blood oxygen levels during sleep time, it could be an indicator. 

It's best to get in contact with a physician who can offer more insight on this sleep disorder.

Most physicians will order a sleep study first, which includes a more sophisticated SPO2 tracker and heart rate monitor, and yields more data than a smartwatch or fitness band. 

6. How do fitness trackers track deep sleep?

It's the same principle as sleep tracking--it's based on heart rate. Your heart rate drops during your sleep, so by detecting a lower resting heart rate for device can measure sleep.

Although your heart rate and breathing drop even lower during deep sleep stages, it really depends on how frequently your device measures your heart rate.

Some sleep stages are short, and maybe missed by your fitness tracker. That's why dedicated sleep studies and sleep trackers are often used to measure deep sleep.