Last week I posted my first impression review on Sense sleep tracker by Hello. This post is a continuation of my earlier post, with more analysis on day-to-day usage after using the device for one week.

The Sense unit that tracks our bedroom’s noise level, ambient light, temperature, humidity and particulate sensors works well all the time. I did not encounter any problem with it. Putting our hand on top of the Sense unit to get green/yellow/red indicator of bedroom condition is fun, but does not really give me much information. Most of the time I ended up opening my iPhone to see the actual charts of temperature, humidity, brightness and noise-level.


Using Sleep Pill as movement sensor, Sense app detects 4 milestones of our sleep: the tine we go to bed, the time we fall sleep, the time we wake up and thetime we get off bed. One of their big promise is the no requirement for a user to press any button to indicate the start of sleep tracking, one thing I have to do everyday with my Fitbit One.

Now, how accurate is Sense’s automatic sleep detection?

Sleep 1

In my first night, it detected the first movement of my pillow as “In Bed” time. Even though it was just a movement to put my pillow to its proper location after I installed the Sleep Pill. The next two hours when I went outside the bedroom was detected as “deep sleep”.

Sleep 2

On the second night, I deliberately tried my best not touching my pillow before going to bed. It detected my “In Bed” time almost correctly. Still incorrect though, because I suspect it detected some movements when my wife moved her pillow and started recording the time for MY sleep.

Morning after second night, I tried playing around with the app and found there is a way to actually adjust our detected sleeping time manually. However, it got awkward because moving my time of “In Bed” didn’t automatically readjust my time of “Fell Asleep”. As a result, it looked that I fell asleep before I reached my bed, like a panda.

When playing around with app setting, I noticed that Sense app is compatible with Apple HealthKit. Somehow its default setting is not active, so I turned on the feature.

Sleep 3

My sleeping time was detected incorrectly again because of pillow movements before bed time. I tried to fix the “go to bed” time and “Fell Asleep” time manually. But somehow the time point of “Fell Asleep” disappeared after I changed the “In Bed” time. I couldn’t find any option to set it again. As a result, on that night I went to bed, never fell asleep, then suddenly woke up in the morning.

I also noticed that my sleeping time were not recorded in Apple Health app even though I have turned on the option in Sense app. I suspected it might have something to do with my habit to turn my iPhone to Airplane mode at night. So I decided to keep my iPhone connected to the Internet for the next few nights.


Sleep 4

I did an experiment. Instead of letting the Sleep Pill detects my start of sleeping time, I detached the Sleep Pill from my pillow and put it on a place where I am sure it will not detect any movement during daytime. When I was about to sleep, I re-attached the Sleep Pill to my pillow right before I go to sleep. Similarly, in the morning after I woke up, I removed the Sleep Pill again. This method worked. Finally I got good detection of my sleeping.

The connection with Apple HealthKit finally worked. I finally saw some data in my Health app. Well, not much data actually. All that’s being sent by Sense app to Health app is just the time of start sleeping and the time of waking up. So my earlier suspicion was right. The connection did not work because I turned on Airplane mode.

Sleep 5

I did another experiment. Since re-attaching the Sleep Pill every night and removing it in the morning felt as a burden, I decided not to attach the Sleep Pill to my pillow case. Instead, I just the Sleep Pill under my pillow and removed it the next morning. The result? The detected time of “Feel Asleep” and “Woke Up” were still correct (obviously they should, because I still put the Sleep Pill on a safe position during daytime). However, the sleep detection got a little bit unusual. It recorded significantly more “deep sleep” even though I did not consider my sleep that night as particularly good. I guess being under my pillow, the Sleep Pill does not detect movements as much as when it was attached to pillow case.

Sleep 6

Since the last experiment to put Sleep Pill under my pillow was considered as failure, I re-attached the Sleep Pill to my pillow case again before sleeping. I sure hope the Sleep Pill’s clip is strong enough to handle re-attachment everyday.

I noticed that the sleeping chart detected by Sense app can change without we did anything. In the morning I got “In Bed” time correctly and “Fell Sleep” time around 15 minutes after. When I re-opened Sense app later at evening, the “Fell Asleep” time was gone and replaced with “Tossing and Turning”. So the algorithm that calculates my sleeping pattern somehow changed its mind during the day, and concluded that I never “Fell Asleep” last night.

Sleep 7

Not much experiment this time. I already got the general idea of what worked and what did not work with this sleep tracker.



Aside from the issue with pillow movements outside sleeping time, I honestly a bit disappointed. When I backed the Kickstarter project, it promised to track our sleep using various sensors. I quickly assumed that other sensors (temperature, humidity, brightness, noise-level and AQI) will somehow got integrated into my sleeping analysis. What I ended up getting here is basically a sleeping analysis based mostly on movement detection using the Sleep Pill.

Yes the Sense main unit does detect temperature, humidity, brightness, noise-level and AQI and presents them in the app. However, the reading are simply presented as line charts and they are completely separated from the sleeping analysis chart. In the end, I was detected as having deep sleep when I was not moving during my sleep. When I moved a lot, it was detected as “Tossing and Turning” or “light sleep”, but there is never any analysis that such disturbance might be caused by the humidity level of that particular time or other factors from the multi sensors. Luckily, this issue should be able to be addressed with software update. Because all the data are already there, they just haven’t used all the data effectively.

Hardware-wise, Sense is a very nice-looking product. Having the Sense sensor in my bedroom really looks good. The Sense app also have nice design, but the algorithm still needs a lot of work. Manual adjustments of “In Bed”, “Feel Asleep”, “Woke Up” and “Out of Bed” must be improved. Adjusting the time manually should never caused a milestone to disappear. This is a really annoying bug. If they managed to improve the app and solve the issues I mentioned, this could easily become the best sleep tracker in the market.


update 12 Jun 2015: I realised that the connection between Sense app and Apple Health app is not really affected by Airplane mode. I had one night with Airplane mode and my sleep data managed to appear in Health app, and another night without Airplane mode and my sleep data was nowhere to be found in Health app.

update 16 Jun 2015: Sense released app update today, promising fixes on issue with Health app integration and other bug fixes.

update 21 Jul 2015: I write a new blog post on my impressions after 7 weeks of using Sense. Read my new post here.