Sense sleep tracking system review

Four months with the Sense sleep tracking system from Hello Inc. haven’t made me a “better sleeper”.

Sense is a sleep tracking system that monitors the bedroom as much as it monitors the sleeper during the night. I’ve had the Sense installed in my bedroom for almost four months and want to share my experiences with it.

It’s interesting to note that the only pages on the Sense product website that calls the device “a sleep tracker” are in the legal and privacy policy documents. All consumer-facing pages explaining the product refer to it by other and gentler words with less negative surveillance-state connotations of privacy invasions in your bedroom.

I’ll go through each component of the Sense sleep tracking system in the following order:

Update (): Hello, Inc. has gone out of business and discontinued Sense. See my postmortem review for further details.

Hardware and sensors

The Sense sleep tracking system consists of the Sense base unit (pictured above), to be placed on a bedside table, and the Pill motion tracker that attaches to the edge of your pillowcase (pictured below.) The base unit features a range of sensors to monitor the conditions in your bedroom, whereas the Pill(ow) tracker keeps an eye out on your movements during sleep. The base unit must be connected to your Wi-Fi network and to an Android or iOS app.

The Sense base unit is a pretty round plastic orb packed with sensors to register the sleep environment. Including an ambient light sensor, temperature and humidity sensor, as well as a particle sensor to keep an eye on dust, pollen, and other particles in the air.

There are no buttons of any kind on the base unit, but you can wave your hand above it and it will light up in a color to give you an indication of how well the current room conditions are suited to provide an ideal environment for a good night’s sleep. Green for ideal sleep conditions, orange for sub-optimal, and red indicate that you’ve got no chance of a good night’s sleep in the current conditions.

The idea is that if your Sense lights up in red, you should pull up the mobile app and see what is going on in your bedroom. Armed with new insight into your bedroom’s current suitability as a sleeping chamber, you could make adjustments to improve it. In reality however, you probably already know that your bedroom is too hot or too bright, and there isn’t much to be done about it. You probably didn’t need a fancy array of sensors to tell you that.

Pill motion tracker attached to a pillow, part of the Sense seep system

The Pill motion tracker.

The Sense Pill motion tracker unit features a six-axis motion sensor that keeps an eye on how restless you are during the night and when you fall asleep. You’ll see little difference in the recorded data if sleep with your arms wrapped around your pillow rather than under your head, or other alternative pillow arrangements.

I’m not sure whether it’s the sensors, the app, or Sense servers that are slow – but what is displayed in the Sense app and the color you see when you wave your hand above the base unit doesn’t reflect the “current room conditions”, as promised. What you get instead are the room conditions as they were 15–25 minutes ago.

If you turn on the lights and play a podcast or some music right next to the Sense in a brightly lit room, the app will show the room as quiet and dark for up to 25 minutes before it retroactively updates to show the room is too noisy and too bright.

Room donditions according to the Sense app

I strapped the base unit on top of a washing machine while it was violently and noisily centrifuging my laundry. The Sense glowed green every time I waved my hand above it until 18 minutes after I started the experiment when it finally turned red. The only sensor that seems to be immediate is the ambient light sensor.

When Sense is so slow to update after you adjust your sleeping environment, it can be hard to use the Sense as an indicator for your bedroom’s suitability as an ideal sleep environment. You can’t check with the Sense to see if any adjustments you make are enough to turn the environmental condition green.

The base unit seems to frequently struggle to stay connected to the Wi-Fi network. Causing it to get a bit warm as it frantically tries to reconnect to Wi-Fi. Any networking problem usually resolves itself, but no data will be collected. I’ve observed this problem cause the room temperature measurement to increase by 1–2 degrees Celsius when Sense finally manages to reconnect.

The Pill will light up the base unit in an assigned color when you shake it hard for a couple of seconds. Even with this clear sign of communication between the two, the Sense app may still show that the “Pill [was] last seen eight hours ago.” This problem also eventually corrects itself, but again no data will be collected while the two devices fail to talk to each other properly.

Sleep Scores

Staying very true to its roots in the Quantified Self movement, the Sense literally puts a number between 10 and 100 on your sleeping environment and quality every night called the Sleep Score. The number is a proprietary measurement incorporating the various data points recorded about the room environment, your movements, and how long you slept.

Sense wants you to sleep for eight hours in a cold and dark room. However, if your personal sleep preferences include sleeping in a warm or lit room, you will never see a green Sense orb nor get a high Sleep Score. There’s no way to customize what Sense considered an ideal sleeping environment, so if you sleep best in a warm room then the Sense isn’t for you.

The pseudo-science used to calculate the ideal sleep environment and your Sleep Score can only be as good as data provided by the Sense system’s sensors. I’ve already pointed out that the sensors can be slow at tracking live events as they happen. I’ve done some experiments with them and also found them unreliable.

Having an alarm clock muffled by a T-shirt go off at 04:40 in the night didn’t even show up in Sleep Summary. Likewise, you can leave your bed at 04:00 and if you don’t return for another four hours, Sense will give you a high Sleep Score even when you weren’t even in bed.

I’ve noticed that my scores seem to correspond extremely well to how long I sleep. for example, a score of 55 is achieved pretty consistently after 5 hours and 30 minutes. Changing the bedroom environment to be hotter and keeping the lights on during the night doesn’t change the score.

Likewise, I get a score of around 65 after 6 hours of sleep, and 80 after 8 hours of sleep. The other sensors seem to matter more at the higher score but the system is easily hacked. Put your Pill sensor at the outer edge of your beddings and throw a T-shirt on top of the base unit. Voilá, your Sleep Score goes to 94 in just 8 hours and 30 minutes.

The app has an option for receiving alerts on the phone every morning with the night’s sleep score, and a separate alert to be notified when the bedroom conditions aren’t optimal and require adjustments when you go to bed. The options sound interesting and would increase the value and awareness of the Sense. The only problem being that these notifications haven’t been implemented still. We’re now two years since the initial release and core features aren’t in place yet.

I haven’t found the Sleep Score nor the Sleep Summary to be of any help. The data is beautifully presented but it’s not anything you can act upon. What do you do with the data? More on this later when I discuss the app.

Kind-of-stupid “smart” alarm clock

Most of the marketing material on the Sense website touting it as a smarter alarm clock that will gently wake you up in the morning when your sleep cycle is at its lightest within a half-hour long wake-up window. This has been done before in both hardware solutions, smart wrist devices, and even mobile apps.

I’ve used hardware and apps based on this concept before, and I’ve previously found it helpful as I’m a heavy sleeper. The accuracy of the light sleep state detection is very slow to update. I can get out of bed and be fully dressed before it realizes that I’m probably in a light sleep state and trigger the alarm. This problem is probably caused by the slow sensors, as discussed previously.

The hand-waving gesture is the only non-app way you can interact with the base unit. Waving your hand above the Sense will light it up in different colors to show the room’s current sleep condition or disable ongoing alarms.

If you don’t like waving your hands above the Sense to disable alarms, you can also switch the lights in the room off and on again. Birds flying in front of your bedroom window casting shadows onto the Sense will also silence any alarms. (I was awake enough to register what happened and thought “I must include this in my review.” But I still fell back to sleep and overslept that day.)

Alarms can’t be disabled on the Sense device before they’ve started. The alarms are disabled by waving your hand in the air above the main tracker. If you woke up early and got in the shower, you must just let it ring to an empty bedroom. Alarms can’t be disabled from the app when they’re less than half an hour from ringing either. This is probably one of the most annoying design flaws with the Sense used as an alarm clock.

Sense has a selection of soft and airy alarms to wake you up gently. All but two of the built-in alarms make an unpleasant noise disruption when the alarm tones loop. Although not by design, it encourages you to turn off the alarm quickly.

Reoccurring daily alarms will after some days or weeks simply no longer go off even though they show as set in the app. They have to be deleted and recreated. Sense has clearly not been product tested on heavy-sleepers that need their alarm clocks to put the fear of death in them to get out of bed.

If you’ve already set one smart alarm for the morning but want one for your afternoon nap too, you’ll likely click add alarm in the alarm list and set up a smart alarm that fits your afternoon sleep schedule. However, the app will complain that you may only have one smart alarm per day but will not offer you to edit the existing alarm or switch the new alarm to be a dumb alarm first.

Sense for couples

The Sense base unit can track two people individually by pairing it against two Pill motion trackers and separate apps installed on each person’s phone. (It will not allow you to connect more than two Pills for anyone enjoying an extra-dyadic lifestyle.) The two Pills are attached to each user’s pillow and must face away from the other person to limit the amount of their motion are picked up by the other person’s tracker. There’s an implicit assumption that each user will stay on their side of the bed throughout the night —. This may not work for everyone.

Sense app showing partners rolling on top of each other during the night

Suggestive icons in the app record special events throughout the night.

As mentioned above, you set alarms by using the Sense app on your phone. In a setup with two users having their apps connected to the same Sense, you would expect it to list the same configured alarms on both phones; allowing both users to administer the alarm clock. Instead, each other has separate alarms and can’t disable alarms set by the other user.

Setting separate alarms on a shared alarm clock makes little sense and can be a frustrating experience if your partner is away one night and you want to sleep in the next morning. The whole system isn’t designed for being used by more than one person at a time. For example, how will it know which person is snoring from audio queues alone?

If there’s only one person in bed for a night, both persons will still be assigned a Sleep Score. If you remove one of the Pill trackers when going to bed alone, that movement will be recognized as that person going to bed even though their Pill tracker remain dead still for the rest of the night.

The app

I’ve already mentioned a few of the app’s shortcomings so it should come as no surprise that I’m not thrilled about Sense’s mobile app. The app is available for Android and iOS, and it’s the only way to interact with the Sense sleep system.

After having used Sense every night for two weeks’ time, the app asked me to tell it when I usually go to bed. Which would have been an understandable question on day one but weird after two weeks of actively monitoring my bedroom and sleep patterns. Answering this very question is one of the reasons for using the Sense, so why is it asking me to answer this question? I’m supposed to ask it! It’s been almost four months now, and the app still asks me the same question about my sleep several times per week.

The few questions the app asks the user to put in has no sense of timing. Which again is bad for a timepiece. For example, it will ask me how my sleep was last night when trying to set the alarm late in the evening or long into the night.

I presume these questions are supposed to calibrate the sensors or give the user the perception that the app is doing something. But it becomes an ill-timed distraction when it can’t be bothered to check what time of day it’s and find a time when it would be suitable to ask them. Right before bedtime, the app should know to be as unobtrusive and little distracting as possible.

Within the app, you can find one or two weekly observations about your sleep habits. These are written exactly like copy texts produced by robotic journalism where a text has a few keywords that are either positive or negative and a variable value or two. These are interesting enough, as you can see how well your bedroom stacks up to that of other Sense users

A sleep system shouldn’t need a competitive incentive or platform among its users, but it’s all harmless enough if a bit silly. What is more annoying about these observations is that you will get the same observation with just tiny variations week after week. After three months of stating every week that my bedroom is too warm, it should spot the trend and recommend that I do something about it. Likewise, if I’m consistently not getting enough sleep, the app should offer me ideas for how to find the time and motivation to get some more sleep. It could even offer to set a sleep-goal and track my progression towards that goal. Instead, you get dull and boring robot texts that are blind to what they’re reporting.

The app is beautifully designed, but it only gives you a very high-level overview of your Sleep Scores and duration on average every weekday. You can’t dig down into the data and identify any real problems.

The data recorded by Sense is only available through the app. I use both the FitBit pedometer and Google Fit through my Android Wear watch and only have the apps installed to collect data. I always use the Web portals to look at the data. I prefer having all the graphs on a larger screen where you’ve some room to see trends and the big picture. Your sleep data is walled off inside an app with no option to view it or export it to a larger format feels like an unnecessary limitation.

The Back button will as often as not quit the app and not take you back to the previous screen within the app. Something users on Android will find most annoying.

The app asks you to provide some generic data like your age, height, and weight. Other than that there aren’t any options available. Except for one option called “Enhanced Audio”. It’s not explained why this is an option nor why it’s disabled by default. The little documentation that’s available doesn’t explicitly state that enabling it will have any consequences.


It’s a beautifully designed product that was rushed to market before being finished to meet the expectations and delivery promise made to the Kickstarter crowd who bought into and preordered the product. I think the designers and engineers at Hello Inc. can make a great sleep tracking product with what they’ve shown with the Sense. The Sense, however, isn’t it.

Sense doesn’t understand what is going on in your bedroom so it can’t help you understand it nor your sleep. There isn’t anything about the product that I like, except its promise of a better night’s sleep through technology. Or at least better insight in how you sleep. The Sense doesn’t live up to either of these expectations. It’s a hard-to-use and expensive alarm clock that doesn’t even do that most basic job well.

After using the Sense system or three months I’ve learned that I go to bed way too late, sleep way too little, and that I’m quite restless before I fall asleep and then remain motionless for the remainder of the night. … but I did kind of know all of that already. It hasn’t enabled nor encouraged me to change in any way. There hasn’t even been a placebo effect or attitude change towards my sleeping. Well, except that I avoid touching the bed before going to sleep to avoid setting off the tracker prematurely.

The Sense is a beautiful piece of hardware engineering, but it’s strongly lacking on the software side. This could be fixed by updates, but Hello have been slow to deliver on these. Wait for the second generation sleep tracker from Hello, or at least another few months for app and firmware updates to resolve some of the many issues.

Check out the Sense sleep system on the Hello Inc. website.