One Night’s Sleep: Oura vs EMFIT vs Garmin vs Vantage

New Oura Ring Review vs Motiv RingHere we have one night of my sleep; last night. For once I would class it as a good night’s sleep. It was just me and my teddy bear.

It was a very late night but that was work-related rather than party-related. And it was enjoyable work rather than the usual stressful stuff.


I had my QS EMFIT under the mattress and the new Oura Ring on my finger. On one wrist was my trusty Garmin Forerunner 935 and on the other wrist was the young pretender; the Polar Vantage V.

I have done these comparisons before for my own benefit but never with 4 devices. So here I am sharing it with you.

EMFIT and OURA both claim to be able to offer HRV insights. Indeed, for the same night (I can show it if you want), both devices broadly agreed with each other for RMSSD and rHR.

You can perhaps spot some ‘vague similarities’ in how EMFIT+OURA assign my time to the various sleep classes but, perhaps, ‘vague similarities’ is being generous.

Nevertheless, as you can see, below, they both agreed with each other on the first BED exit event at 7am. Garmin did NOT EVEN SPOT THE BED EXIT event and yet would still like you to believe that it can correctly assign my sleep classes?

Polar DO spot the bed exit but do not pretend to try to guess my sleep classes. Instead preferring to give me a measure of sleep continuity. At least THAT scores quite highly as a ‘hmmm’ RATHER THAN a ‘meh.

Please feel free to click and closely examine the charts (but I wouldn’t waste your time) and then read on afterwards

QS Emfit

EMFIT – Cliackable


Oura Ring

Polar Vantage V

Garmin Forerunner 935


Garmin: The pink is bed exit at 9:30 NOT the real bed exit 2 hours earlier


Summary Table & Intricate Analysis

I determined a few correlation coefficients but then decided that the best conclusion was that “I got about 7 and half hours sleep” 😉

If you can make any better conclusions on the charts, above, or the sleep stage data, below, I’d love to know

EMFIT 1:59 01:07 03:45 6:51
Garmin 935 not stated 04:00 05:41 9:41
OURA 04:37 00:45 not stated 7:30
Polar not stated not stated not stated 7:15

When I decided to get up, I did a Polar Orthostatic Test – which told me I was ‘good to go’ like it usually does these days (via ‘Recovery Pro’). And I even got blast-from-the-past BioforceHRV to agree that I was ‘good to go’.


Hey. One night’s sleep and all that. Sample of one.

  • The Garmin data is just simply wrong. It can even get the 70kg (ish) of me getting out of bed and traipsing off to the toilet right. How on earth can it possibly distinguish my deep sleep stages? No doubt your Garmin data is more accurate than mine.
  • Polar gets the basic ‘hours’ right in a probably more honest approach. At least they don’t pretend to know the stuff that the major fitness companies pretend to know – and I include the likes of Fitbit et al in that sweeping statement (specifically: sleep stages)
  • EMFIT and OURA both seem plausible to me. I secretly hoped they would agree with each other. But I didn’t expect that they would. I reckon one of them is the most accurate device at a deeper level and properly able to determnie sleep classes….I just don’t know which one it is 🙁 – you can be sure that both will have their own studies saying it is them!
  • EMFIT and OURA did broadly agree on the night’s HRV trend and rHR trend, which I did find vaguely (& pleasantly) surprising. From that I would have expected similar conclusions on sleep stages. However EMFIT has the advantage of being better able to detect ‘gross’ body movements, some of which OURA might miss. Historically that’s why I have tended to trust EMFIT as one of my indicators of readiness (through other measures it produces)

Take Out: Don’t work late, get a blue light, don’t drink alcohol, coffee or have a good time [insert your own unsubstantiated conclusion here] 🙂

These opinions are all my own. Let’s face it nobody else would want them. If YOU have any opinions other than ‘Eesh’, I’d love to hear them

Support this site with purchases at these partners - should click to a local choice in your country

8 thoughts on “One Night’s Sleep: Oura vs EMFIT vs Garmin vs Vantage

  1. I feel you. My experiences with other devices have matched yours in terms of ‘wtf’? I’ve used a Garmin Chronos (I know it’s big, but you get used to it) and a phone app (sleep as android, I put the phone under the pillow) until i got the oura v2: I can say that the garmin got much better over time (meaning it went form awful to acceptable), while sleep as android stayed acceptable. Obviously the Oura ring is much better, but it’s somehow a must as it is specifically designed with that in mind (and it’s a new generation technology)
    That said, I did all of my ‘data comparaison’ using the super scientific formula called ‘gut feeling of the night’s sleep’ beacuse the numbers were all over the place. For now I think we are in a similar situation to running with power (or vo2 max extimations for that matter): we have very different values , but we hope that they can be at least consistent with each other. My two cents
    Good article!

    PS: I’ve always been tempted with the Emfit Qs, but ultimately decided against because I have a hunch they are to release a new one soon..

  2. I suspect there’s quite a broad range of difference in evening/morning routines (both pre-bed and even things like sitting in bed and reading on phone), that drive how well these different devices track fall-asleep/wake-up time.

    For whatever reason – almost every device I try manages to get fall-asleep/wake-up times spot-on for me (usually within a couple minutes). Garmin, Polar, Suunto, Fitbit, even 3rd party Apple Watch apps – nailed it. Rarely is it off, and when it’s off, it’s usually due to an early morning kid waking up around 5:30AM for something and then going back to sleep, that tends to trip up some. But otherwise, solid.

    As for the rest of the data, shrug, all seems like a guess to me.

    • yes. EMFIT for one does get the ‘in bed’ time right.
      i think i’d gone out for a run before garmin got me out of bid (that was a semi-serious joke but i had had breakfast)

  3. My night data from FR935 were so ridiculous that I’ve bought Emfit. Now I sleep much better, knowing that I do get some deep sleep which FR935 is consistently denying from me.

  4. I am wondering if the Vantage V will be better than my V800 at detecting sleep. The V800 has me as asleep, then it says that the watch has been taken off for some of the night and then put back on. This may just mean I am world class at stay still when asleep or my kids/wife are removing my watch in the night and putting it back on just for a giggle.

Leave a Reply

Your email address will not be published. Required fields are marked *