I was asked by Neil of “Yeah, Another Blogger” fame how my Galaxy Watch could determine when I’m in REM state. This was in reference to Thursday’s “The Biological Clock” post on this blog. I couldn’t provide a satisfactory answer, so I asked my computer nerd friend Tony how the sleep mode works. Now, I can provide a rough answer to Neil’s question and tap out a short blog post all at one try.
My Galaxy Watch is a few years old–it isn’t the latest version that Samsung is currently manufacturing so keep that in mind. The gadget is reliable and accurate enough for noncritical approximation of sleep cycles. If you are having sleep problems, a more accurate diagnosis can be had at a sleep laboratory at a hospital or certain medical clinics. Ask your physician about this. (I’ve spent a few nights at our town’s sleep clinic with electrodes attached to the body so technicians could observe my sleep patterns. The sessions were helpful.)
Meantime, modern smart watches are nifty devices that are capable of many tasks that our cellphones can do plus a few additional things. One of them on some watches monitors sleep. The Samsung watch app is rated highly among others like Garvin and Fitbit. I bought my Galaxy Watch in 2019 for less than $200 at the local Target store.
I put the watch on my left wrist about an hour before bedtime so I can do a couple of tests. I like to use the stress app to determine how uptight my body is. The other pre-sleep test is to obtain my heart rate from another app. Then after climbing into bed and getting comfortable I select the “Goodnight” mode and turn it on. I have mine configured to also monitor REM sleep, this sacrifices a few extra minutes of battery charge because more resources are required; but that’s not a problem.
When sensing for REM sleep, the watch takes my pulse every ten minutes. It also engages the watch’s built in accelerometer. The human REM cycle manifests as more active brainwaves which are accompanied by faster breathing, increased heartrate, and some muscular movement.
The Galaxy Watch measures the pulse with an optical sensor on the back of the watch case. Muscle movement is obtained by detecting movement with its accelerometer. An accelerometer measures gravity and movement then records it on a memory chip. An accelerometer uses the same principle as a basic pedometer.
Thursday night, I followed the usual bedtime routine for the watch and drifted off to dreamland. Unfortunately, thunderstorm activity awakened me a couple of times, so I did not receive a proper amount of sleep.
The Galaxy Watch affirmed this by recording fewer hours my body rested. Despite the thunderstorms, I was only awake 8% of the monitored sleep time. I closed the monitoring mode of the app, then checked the data. I was pleasantly surprised that REM sleep comprised 25%, light sleep 65%, but deep sleep (not shown in the photo) was a measly 2%. Clearly, I need to spend less time around noisy weather conditions.
This watch has many daytime functions as well, but the main reason I purchased the device was to monitor my sleep. I’m pleased with the relative accuracy of this gadget.
The Blue Jay of Happiness quotes legendary baseball player, Yogi Berra. “I usually take a two-hour nap from one to four.”