The importance of sleep and how best to measure it

Here at Sports Orthopaedic Specialist Charles is really interested in sleep, over-use injuries, recovery from sport and recovery from surgery. He is sure that god sleep means good recovery and hospitals are not conducive to good sleep!

The first part of fixing a problem is measuring the outcome so we are really interested in a simple cost effective way of quantifying good sleep.

Over the years Charles has investigated a whole range of devices for measuring sleep and here is his own personal opinion on the current offering:

Garmin Vivosport 2

Charles used the Garmin vivosport 2 which measures both resting heart rate and heart rate variability (HRV). From the heart rate and motion accelerometers sleep is calculated. It actually only does HRV on demand – not constantly. Charles used this for three or four months and looked at the sleep metrics. Unfortunately he found them to be quite inaccurate often recording sleep when he was sat watching television of an evening or reading a book. The sleep scores didn't really seem to correlate with when he was asleep and certainly didn't seem to correlate with self-perceived recovery. The device was quite good at measuring stress during the day and the stress scores did seem to correlate with stressful events ut it would only do this on demand. It has a lot of other really good features too (the best being to make your phone ring when you cant find it!).

The device has to be worn on the wrist and Charles found this a little inconvenient at work where he's constantly washing his hands and wrist watches are banned and, and also at night time. Overall for what he was looking for the Garmin did not do the trick and the data did not seem particularly reliable.

Fitbit Charge 2

Charles used a Fitbit for more than a year to measure his sleep. He found this to be quite reliable at measuring total sleep, REM sleep and deep sleep in. He didn't use the device in the day as it didn't seem to add much, but the sleep metrics were really useful interesting and motivating. He managed to use this device to identify things that helped his sleep and things that held hindered his sleep by keeping a careful diary, the app and software didn’t facilitate that. Similarly he tried to correlate that with his own athletic performance, and this was pretty accurate, but hard work to quantify and collate the data. Overall the product seemed to work well, and was a good device for measuring sleep, but the app did nothing to help analyse the data.

Oura ring

Charles tried the Oura Ring full of optimism. It is super accurate and measures things like body temperature as well as heart rate and HRV. It's important to get a ring that fits so it has been difficult to lend it to anyone else and see how it's worked for them. It did record good sleep data, but he found wearing the ring to be awkward and cumbersome at work and in the gym. In short it did not fit with his lifestyle. Working as a surgeon it needed to be removed very regularly for operating (when the HR data would be really interesting. It was also quite bulky and clumsy to wear during sport such as lifting weights or on the bike and it would get scratched and damaged. The data was quite useful but perhaps not as accurate as the Fitbit in his opinion and there was not good correlation of data when he wore the Fitbit the Garmin and the Oura all at once.

Because of the difficulties wearing it and the fact that the data was not particularly useful to him he ended up giving up on the Oura ring. Also of note it would be no good for using with patients as sizing was critical and it could not be transferred easily from person to person.

Whoop 3.0

The whoop is a slightly different device and one of the big plus is it that can be worn on the arm or the wrist. It can be worn 24/7 quite easily and it can even be kept on whilst charging because there is a small battery which can be charged from a USB charger which then clips onto the device to charge the internal battery in the device. This has been really appealing to Charles. The only time it needs to come off is for cleaning and it's waterproof so it can be worn in the shower. One of the downsides is if you wear it all the time and wear it for sport the strap does need regular cleaning or it can start to smell!

Charles thought the data was really really useful. The sleep data seems to be the best of all of the devices he's tried and the split between REM sleep deep sleep and light sleep seems to be really accurate. The app gives sleep scores to simplify the data, as well as recovery metrics and cardiovascular strain metrics. These seemed to be useful and Charles has used these to tailor his training to his recovery. Interestingly on the days where it said he was fatigued and he felt good he would then try and do sport and find actually that he would underperform so if anything the data from whoop has better than self perception!

Charles is really encouraged by the sleep data and he's used this to modify a number of factors to help him sleep better. The software on the app actually makes this very easy where the system whereby you record a few key things that you did the day before. The app presents you with a range of yes no questions when you wake up before you see how you slept and over time the software will automatically tell you what's working well for you and what working badly for you. This seems to be a really easy way of understanding your own sleep and ways to improve it.

So far ( and Charles is hanging on the Whoop for now) he has found this really useful for sports and avoiding over training, but also it appears that this may be the most promising thing for monitoring patients sleep and patient recovery following surgery. The subscription model is a bit frustrating in that there is no upfront cost but you have to commit to at least 12 months of subscription. If you fall out of love with the product you're still committed to keep paying. Also the fabric straps are quite expensive to replace given what they are, and whenever you buy anything from the company the tax and shipping costs from America seemed to be a bit over the top.


We have found Whoop to be the best product for measuring and improving your sleep. The device works well and does not get in the way of day to day life. The app is easy to use, does not require you to analyse your data too much, and has led to tangible improvements in sleep.

The next step will be to start to measure sleep in patients before and after surgery.

If you are intersting in trying whoop use Charles' link to get a free Whoop and the first month free HERE

Posted on Sep 01, 2020

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