Sensors and Sensibility

Sleep data - Comparing Hello Sense, Fitbit Charge and Bellabeat Leaf

Thought it might be fun to run a comparison of sleep logging on a few of my devices.

For reference, I wore the Fitbit Charge on my left (non-dominant) wrist, the Bellabeat Leaf clipped to the neckline of my night vest and the Hello Sense is of course clipped to my pillowcase. I sleep primarily on my side/smushed partially face-down and I'm quite a light-sleeper.

In terms of data points I've recorded, here's a break down:

So, let's have a look at the numbers!

I've got 3 full days of data, and one partial. Why so little? I forgot to record the Sense data each morning for a few days and it turns out you can't go back and look at previous nights. Major fail for the Hello Sense right there. I'm also missing a night of the Leaf's data because I forgot to put it on. Update: The friendly Hello Sense people just emailed me to let me know I can go back and see previous nights data! The gesture was a little non-obvious - but a slide right will go backwards.

Fitbit Charge Hello Sense Bellabeat Leaf
Monday Sleep score 96% 77 -
Total sleeping time 7h54m 6.7h -
Deep sleep 7h2m 2.5h -
Times woken 2 0 -
Fell asleep 23:56 0.31 -
Wake up 07:56 07:12 -
Out of bed ? 08:35 -
Tuesday Sleep score 93% 81 97%
Total sleeping time 10h11m 8.9h 9h24m
Deep sleep 8h49m 2.7h ?
Times woken 2 0 1
Fell asleep 22:41 23.58 23:07
Wake up 08:51 8.52 08:42
Out of bed ? 8.48 ?
Wednesday Sleep score 97% 78 98%
Total sleeping time 9h36m 9.9h 8h58m
Deep sleep 8h56m 4.8h ?
Times woken 3 0 2
Fell asleep 23:39 23:17 00:19
Wake up 09:14 09:13 09:39
Out of bed ? 09:24 ?
Thursday Sleep score 95% 81 76%
Total sleeping time 10h7m 7.6h 5h32m
Deep sleep 9h35m 3.1h ?
Times woken 2 0 0
Fell asleep 22:43 23:06 01:36
Wake up 08:49 06:42 07:08
Out of bed ? 09:01 ?

On Wednesday, the Sense alarm failed and didn't wake me up, so I overslept and on Thursday only 1 of two Sense alarms went off (I reported the outage, and I think they know what it was and fixed it). Thursday night I definitely got up at least twice. I had a Leaf alarm set every morning, and although I felt it go off once (because I was already awake), it was never the thing to wake me up. The Fitbit alarm works well and has yet to not wake me up when used. For reference, my first alarm in the morning goes off at 8:00am (lucky me) and then a second to get me up at 8:25 if I haven't shifted by then.

Which feels more accurate?

Based on what I know about my own sleep habits and routine (don't judge my lazy ass), the Fitbit Charge data fits best and I'd take that one as feeling most accurate - not having any proper professional equipment strapped to me, I can't be certain, of course.

Comparing the BellaBeat Leaf to the Fitbit data, it does seem to be pretty far off the mark - often not noticing that I've fell asleep until after the other systems. It was also the weakest in terms of the amount of data and breakdowns in the 3 systems.

The Sense seems intermittently accurate and is prone to believe I'm awake a lot earlier than I generally am. I'm very surprised that the Sense hasn't noticed when I've been out of bed at night, but I wonder how much bed sharing effects that (it often just notes "you and your partner were both restless" at certain times that I suspect may be when I've been up or awake).

Having said that, I don't think any of them are accurately recording how much time I spend in quality sleep, but I don't particularly expect a system that relies solely on tracking movement to be able to do that. Make of this data what you will, but the bottom line on sleep data by fitness trackers should probably be to take what they tell you with a large pinch of salt.