While some of the big names like Apple and Garmin took quite a long time to develop the sleep tracking feature on their smartwatches, the Chinese brand Xiaomi had been installing this feature as standard on some of its earliest models as early as 2014.
Thanks to a host of sensors on the small-yet-mighty Mi Bands 5 and 6, sleep tracking is not only possible, but accurate even without the use of sleep monitoring apps. This makes these bands a popular option for those looking to monitor their daytime activities and have the device track nightly activity, too.
The Mi Bands 5 and 6 are the latest releases from the brand. They have updated sleep tracking features compared to earlier models and have a better battery life to boot, making them great all-around devices. These devices will not only provide you with clear data on how you’ve slept via the Mi Fit app, but they also go the extra mile to tell you ways in which you can improve the quality of your nighttime regime.
How Do Mi Bands Monitor Sleep?
Packed with intelligent features, Mi Bands 5 and 6 have a range of sensors and software algorithms that work in unison to monitor your sleeping activity. First, the device makes use of an accelerometer and a gyroscope, both of which function on a 3-axis design, so any kind of movement is detected, even those slight arm twitches you have as you dream or when you roll over in bed. This helps highlight restless periods at night.
As you move into different periods of sleep, your motion is detected and fed back to the algorithm, which can determine with high accuracy which level of sleep you are in. For example, when your heart rate drops slightly and your movement becomes more still, this is an indication of light sleep. Both of these features become exaggerated as deep sleep is achieved, with a much slower heart rate and virtually no movement.
One of the main ways your body reacts as you move from light sleep to deeper levels of sleep and eventually the rapid-eye-movement (REM) stage is by changing your heart rate. This is detected by a built-in optical monitor that uses photoplethysmography. Not only can this clever sensor detect your heart rate at any time, but it also knows when you are swimming, running, cycling, or moving from light to deep sleep.
On top of these features, both the 5 and 6 generations of Mi Bands can take a reading of your blood oxygen levels as you snooze. Data like this can point towards issues such as sleep apnea, in which you don’t take enough oxygen into your body. While you can’t make an accurate diagnosis on this alone, the Mi Band’s readings do have the potential to highlight developing problems.
The Mi Band 6 takes things one step further and uses respiration rates calculated by the optical sensor to decide at what point you fall into REM sleep.
If you fall asleep during the day, the Xiaomi devices pick up on this and will track that nap automatically, something that many other smartwatches and trackers fail to register accurately.
How to Set Up Sleep Monitoring on Mi Bands
On the Mi Bands 5 & 6, you can set up sleep tracking by opening the Mi Fit application. Select your profile and choose the name of the device to pair it with your phone. Scroll down to the option tab called “Heart Rate Detection” and select “Detection Method.”
Once this opens, choose the Sleep Assistant option. After you’ve accepted the terms regarding battery life (the sleep tracker will tend to drain the device over the many hours you’re sleeping), just return to the main menu and view the Sleep data.
All the results are displayed on the phone in graph and ring form, allowing you to view and analyze how your metrics, such as heart rate and breathing, changed over the course of the night.
How Accurate Are Mi Bands at Monitoring Sleep?
Unlike Garmin’s sleep monitoring feature, which requires you to set your bedtime and wake-up time to monitor your sleep, Mi Bands are completely automatic. So whether you nod off on a long train journey or fall asleep reading a book, the Mi Band will use its myriad of sensors to accurately detect when you fell asleep.
On top of this, the Mi Band claims to be able to monitor the way you move from a light sleep to deep sleep, and eventually to REM, over multiple nightly cycles. It was discovered that a popular app called Sleep Cycle did not work very effectively on the Mi Bands, and had difficulty discerning whether the user was waking or sleeping, which affects the record of total time spent sleeping and the calculations based on that.
The depth of data measured is a big plus, and the device gives a point score for how well you slept, though this doesn’t always match up to what is recorded on other devices. When Apple Watch sleep tracking was compared with that of a Mi Band, the sleeping times recorded varied between the two as little as 17 minutes to as much as 2 hours.
What Does the Mi Band’s Accuracy Mean for Your Sleep Data?
Overall, the Mi Band 5 & 6 seem to be as accurate at colecting sleep data as any other smartwatch. When it comes down to it, it’s not really the sensors’ detection abilities that are questionable when it comes to accuracy–the breathing rate and heart rate are recorded within a small margin of accuracy–but as with all sleep monitoring devices, it’s actually the algorithm that assesses the data and categorizes light, deep, and REM sleep that seems to be the issue.
This is probably due to the fact that individual sleep patterns vary so much, and although a decrease in heart rate in some people indicates falling asleep, in other people it may fall when they are simply resting and watching TV. It depends on how much activity they undertake through the day and their physical fitness too, as well as stress levels. Sleep monitoring on the Mi Band 5 & 6 has a lot to offer–but always take the data with a grain of salt.