Sleeping With The Apple Watch

It’s been only 6 days since the HeartWatch app was launched. It’s been quite an unexpected success. Top 3 in Health & Fitness in loads of App Stores across the world, and even top 10 overall in a few. It seems a lot of people want to unlock their heart rate data from their Apple Watches! Plus 76% of installs are continuing to check their heart rate every day (100% anonymous, no tracking, ever).

The number of emails has been quite remarkable. As an ex product director in a former life, I love getting product emails from customers. I don’t care if they are complaints, compliments, suggestions or just stories. Every one is incredibly valuable and is one of the best ways a product can improve.

App Store reviews in contrast are much more about sentiment. It’s a way of expressing love (please do) or hate, and whether you want to see their app die or keep going. There is no dialogue. Hence you can’t help anyone that might be confused - as much as you’d love to, and never have enough information to steer product direction. Anyhow, I digress.

Sleeping with the Watch is popular

By and far the most popular request was supporting the ability to sleep with the watch and using this data to both track sleeping heart rate, and, correctly determine waking time. So I messed up here a bit! I had no idea!

According to a recent Wristly survey,

…the fun tidbit that we discovered is that 11% of our panel also sleep wearing their Watches and only charge their batteries in the morning while they get ready to go. When one considers that the Watch doesn’t yet support any sort of sleep monitoring capability, this says quite a lot regarding the attachment of some owners to the product. The primary reason given as to why they wear their Watch while sleeping is the ability to use the taptic engine as a wake up alarm so as to not disturb their partner.

I have a strong feeling this may be growing too.

edit: 12 Feb 2016. HeartWatch 2 is now available. It now has a Watch app with a built in sleep tracking function and the iPhone app now overlays restless data over heartrate. Its use is entirely optional as the app will continue to function with your favourite 3rd party sleep tracking app whether on the Watch like Sleep++ or any of the various iPhone apps that write their sleep data to HealthKit. The only thing you need do it wear your watch to bed as it needs to get the heart rate data.


The most popular app for this, according to the emails I received was Sleep++. So, of course I downloaded and started experimenting on myself.

My main concern was about charging. My Watch is usually somewhere around the 55% mark when I put it on its charging stand. In practice, it turned out not to be a concern at all. I changed my routine a little. I generally read before going to sleep, so I’ve been putting the watch on the charger while I do this. It’s always now 100% before I go to sleep.

Following the Sleep++ recommendation of putting the Watch in flight mode when sleeping results in very little drain. So I am starting the day with around 96–98% charge! Concerns allayed!

edit: 12 Feb 2016: You don’t really need to go into Flight Mode. Do not disturb is fine. There’s very little difference.

One important thing I learnt (the hard way). Make sure that you enable HealthKit support in Sleep++ before using it for the first time on your Watch.

Turn this baby on before doing anything.

From there on in, it’s very simple. Just press Start Sleeping on your Watch when you want to start sleeping, and then Stop Sleeping when you wake up.

Sleep++ uses the motion chip data in your Watch to provide you with a summary of how active you were during your sleep. You then end up with something that looks like the screenshot below.

HeartWatch Sleep

So now, of course I was fascinated to learn what my heart was doing while I was asleep. So I added a new sleep section to the day summary. As long as you enable HealthKit in Sleep++ it will automatically appear in HeartWatch. It’s at the bottom so it gets out of the way once your day fills with activities and uses the same at a glance tile based colour scheme that lets you perceive rather than read. The day it will appear depends on when the sleep finishes. This now means that if you commence a sleep the day before that ends the next day, your day summary will now automatically commence from when this sleep began and the previous day will end earlier.

As with the other summary tiles and zonal summary bars, you can touch any of them to zoom into more detailed information. In the example below, we touched the average BPM tile.

I decided to superimpose the the heartrate timeline over the Sleep++ motion timeline. Manually via screenshot (for now), to see what I could glean.

What’s interesting is that high readings and low readings are generally achieved when there is no motion. This might fit in with idea that REM sleep tends to have higher heartrate and deep relaxation a lower heartrate. However, it has not been a typical last few days at all, so this will be something to monitor and study over time.

Now, all of this was done in a single long day. So, treat it more as a first step, and realistically a bug fix for not considering sleep.

Waking Heart Rate

Sleep and waking heart rate are of course intrinsically linked. Adding sleep means that a much more accurate waking pulse can be taken. As always, the best way is to flick up the heart rate glance, and relax in bed with nice slow controlled breathing. About 30 seconds of this gives a nice accurate sample.

For those that don’t want to track sleep, it’s also now possible to change the minimum automatic wake read time. So, if you get up earlier or much later, this is a parameter.

Finally, some people don’t want to be bothered with tracking waking heart rate. So now you can turn it off.


Two bugs were also fixed. Presenting 24hr time for our European friends and one that was a bit of a doozy. Critical really. Exiting the app while in the detail view and coming back in after an elapsed period of 2 minutes would return to a non-responsive summary screen. Argh. The only remedy a force close.

So, version 1.1 is now submitted to Apple and should be out soon.

What’s Next

There were many other requests. Workout trend tracking, a weekly summary and nett change, a glance and simple watch app and lots more. These need more than a day though!


If you download Sleep++ and enjoy it, please support the developer by paying for ad removal. It helps keep good software cheap. Similarly, if you are enjoying HeartWatch, please tell a friend. There’s are tons of improvements to come.

And please keep emailing. The suggestions are terrific!


Download HeartWatch on the App Store.

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