On a couple of nights, I logged my heart rate with my Mio Alpha HRM watch and I compared the results with the sleep log I get with my Fitbit One. In both cases, these were "good" sleeps, as deemed by Fitbit (98-99% "efficiency"), and their duration was about the same (about 7 hours). During the first night (November 26, 2013), I used the Runtastic Pro app on my Android smartphone (Nexus 4). With Runtastic, I only get a graph, as well as the average and maximum heart rate during the logged "activity". The curve on the graph only includes snapshots every 2-3 minutes (it's possible to read them by hovering the mouse on the graph, in the Runtastic website). Here is the comparison Fitbit vs. Runtastic: During the second night (December 21, 2013), I used the BLE Heart Rate Monitor app, also for Android. That app didn't create a graph, but I could export the raw data as a CSV file (I had to purchase a Premium in-app feature for that), which I could import in Excel in order to create my own graph (see below). The CSV file included almost second-by-second data (23,800 HR values in total!), so it provides much more detailed data than Runtastic. I was also able to add a linear trendline in Excel (a similar trend can be observed on the Runtastic graph). Here is the comparison Fitbit vs. BLE Heart Rate Monitor: It was interesting to see that even when sleeping, the "resting" heart rate is not a flat curve, there's quite a lot of variation. Has any of you performed similar experiments?
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