Coros Apex Sleep Tracking: How Does It Work?

Sleep tracking is a feature that is supported by all COROS watches, including the APEX Pro. The watch automatically recognizes and tracks sleep 24 hours a day. It can monitor sleep status by detecting the user's heart rate through the HR sensor. Sleep tracking is affected by how the watch is worn; if it is loose on the wrist or if the user's arm has frequent movements, the tracking will be impacted. To receive the most accurate tracking, the user should set up the sleep start time on the COROS app as close to when they actually fall asleep as possible. Sleep lasting less than 3 hours is categorized as a nap, while sleep lasting more than 3 hours will receive an overall sleep quality assessment and have sleep stages recorded.

The Coros Apex tracks sleep through heart rate monitoring

Sleep tracking will be affected if the watch is loosely worn or if your arm has frequent movements. To ensure the most accurate sleep tracking, the watch should be worn properly on the wrist so that the HR sensor can detect your heart rate and monitor your sleep status. The HRV is continuously measured in 10-minute intervals during sleep.

Sleep lasting more than 3 hours will receive an overall sleep quality assessment and have sleep stages recorded. Sleep that lasts less than 3 hours will be categorised as a nap and will not receive an overall sleep quality score. The Coros Apex will track separate sleep periods within the same day. Two sleep periods will be merged if there is a gap of 1 hour or less in between and there are no obvious activities such as workouts or steps.

The Coros Apex tracks all stages of sleep except REM. This includes deep sleep, light sleep, and rapid eye movement (REM) sleep.

Sleep tracking is affected by how the watch is worn

Sleep tracking devices, in general, make some estimate of how much you are actually sleeping. They do not measure sleep directly but instead often measure inactivity as a surrogate for estimating sleep. Most sleep-tracking devices use body movement and sometimes heart rate data to make their estimates of nightly sleep. As we move frequently during all stages of sleep, movement provides few clues about what sleep stage we are in. Many sleep devices also fail to differentiate one stage of sleep from another based on motion alone.

Some sleep-tracking devices also look at heart rate changes during sleep to estimate how much time is spent in each sleep cycle. Devices that incorporate heart rate data tend to be slightly more accurate when measuring sleep duration because heart rate fluctuates during different sleep stages. However, even in devices that do track heart rate, many experts are still uncertain of their accuracy because of the limited research on them and because of the differences between each device. For example, one study of heart rate sleep trackers showed that two consumer devices tended to underestimate the amount of deep sleep wearers obtained by as much as 46 minutes.

Sleep tracking is a bit difficult on a watch. Sleep phases cannot be determined without measuring brain activity. Sleep time is more interesting because you can do something about it, and if you see you are awake a lot in the middle of the night, you may need to seek help.

Sleep tracking is also affected by arm movements

All COROS watches, including the APEX Pro, support 24/7 sleep tracking. The sleep algorithm used depends on the watch model. The watch can automatically recognize and track sleep 24 hours a day. However, sleep tracking is affected by arm movements and how tightly the watch is worn. The HR sensor on the watch detects your heart rate to monitor your sleep status. If the watch is loosely worn or the arm makes frequent movements, the HR sensor may not accurately detect your heart rate, impacting the sleep tracking data.

To optimize sleep tracking, it is recommended to wear the watch properly on the wrist. The HR sensor relies on consistent skin contact to detect heart rate variability (HRV), which is measured continuously in 10-minute intervals during sleep. By closely monitoring HRV, the watch can determine your sleep status and provide insights into sleep quality.

Additionally, specifying your Sleep Time and Wake Time manually in the COROS app can enhance sleep tracking accuracy. Setting these times helps the watch determine when to enter Sleep Mode, minimizing interruptions by adjusting the display settings. If you fall asleep before your designated Sleep Time, the watch will automatically enter Sleep Mode. Conversely, if the watch detects you are awake before your Wake Time, it will exit Sleep Mode and resume normal operations.

While the COROS watch provides valuable insights into sleep patterns, it is important to recognize its limitations. Sleep tracking on the watch is designed to help monitor your overall wellness but is not a certified medical device. For any health concerns, consulting a qualified healthcare professional is strongly recommended.

Sleep of less than 3 hours is considered a nap

The Coros Apex watch does track sleep. All Coros watches support 24/7 sleep tracking, with the sleep algorithm used depending on the watch model. The watch will start checking if you are asleep two hours before the sleep start time. If you fall asleep 30 minutes before the sleep start time, the sleep tracking will start then.

Napping for longer than 30 minutes can leave you feeling sluggish, groggy, and more tired than before. The exception to this is if you are sleep-deprived and can complete a full sleep cycle, which is at least 90 minutes. A brief nap of 10 to 20 minutes can increase alertness for a couple of hours after the nap, with less grogginess, and does not disrupt subsequent sleep at night. Studies have found that daytime naps of 10 to 30 minutes can increase performance and productivity at work.

The optimal amount of sleep each night is seven to nine hours. Getting more or less than this is linked to cognitive decline, obesity, heart disease, and premature death.

Sleep tracking is improved with the latest firmware update

With this update, your COROS watch can automatically recognize and track sleep 24 hours a day. Sleep lasting more than 3 hours will receive an overall sleep quality assessment and have sleep stages recorded, so you can understand the specific duration of each sleep stage: deep sleep, light sleep, and rapid eye movement (REM) sleep. Any sleep that lasts less than 3 hours will be categorized as a nap. Sleep quality is your overall "sleep score," evaluated based on overall duration of sleep and sleep stage recordings.

To receive the most accurate sleep tracking, set up the sleep start time on the COROS app as close to when you actually fall asleep as possible. You can also manually set a timed nap from the toolbox menu. From the main watch face, long-press the Back button and scroll to the Timed Nap widget to select any duration between 15 and 90 minutes. Your watch will alert you when the timer is complete, and the sleep data will be tracked as a nap and included in your sleep summary for the day.

For best results, specify your Sleep Time and Wake Time manually in the COROS app. Setting the Sleep and Wake time helps the watch determine when to enter Sleep Mode, an automatic setting that quiets the display to minimize interruptions. If the watch detects that you are awake prior to your established Wake Time, it will exit Sleep Mode and resume normal operations (regular backlight and display settings). Conversely, if the watch detects that you've fallen asleep before your normal Sleep Time, it will enter Sleep Mode automatically.

Frequently asked questions