Refine Naturals™

Race of the Sleep trackers: Fitbit vs Oura vs Whoop vs Garmin vs Apple

Is your New Year resolution to step up on fitness and focus on restful sleep? Well, these wearable coaches will help your resolution last longer (than last year!). To make choice easy in this competitive market, we bring to you a comparison of their sleep tracking potential.

The contestants:

Sleep metrics: Who provides some extra stats to ponder on?

Sleep data is generally based on heart rate variability and body movements. The following sleep metrics are provided by these devices:

Apple Watch 6: Only tells if you were awake vs asleep and the total hours you slept, no staging sadly.[1]

Fitbit Versa 3: Apart from total sleep time and awake time, it also gives you a ‘sleep score’ (an easily digestible summary of your sleep) and sleep staging.[2]

Garmin vivosmart 4: Provides total sleep time and the 4 stages: deep, light, REM and awake. ‘On device’ Sleep score display is available on costlier devices such as the Fenix 6.[3]

Oura Ring: Apart from the triad of sleep hours, staging and sleep score, the Oura ring also provides ‘readiness score’ and ‘activity score’. These metrics are supposed to tell you how well you rested, how ready you are to take on challenges during the day and how far you have reached your activity goals.[4] All this along with the excitement of wearing a ring!

Whoop Strap 3.0: Sleep hours, 4 stages and sleep score is just the beginning, this Strap also ‘coaches’ you on how much sleep did you actually need, how well did you recover by last night’s sleep how much are daily activities ‘Straining’ you numerically.[5] Whoop is a winner in this category!

How accurate are the measurements? Instead, let’s look at how bad they are:

Even though this interesting study done in 2019[6] did not use the latest devices, the algorithms are the same across generations, for example, Fitbit Ionic and Fitbit Versa would use the same algorithms to calculate Sleep metrics. We can clearly see the device which made the least errors: Fitbit[6]

Green vs Red light sensors

While you may not have paid attention to the lights on the back of your watch (they measure heart rate and oxygen saturation), red and infra-red lights have been proven to penetrate skin deeper than green lights, especially in people with darker skin.[7] However, red light scatters not only with red blood cells, but with other tissues as well. Hence, having a combination of these sensors would work out best. With Apple having a great hardware and buying the Finnish company Beddit in 2017, it looks like they are going to improve their algorithms soon.

The verdict: Fitbit is not only one of the most accurate of the tested sleep trackers, but is also one of the most studied one. Oura and Whoop are also nearly as accurate. Apple believes that a lot of data can be confusing and shies away from sharing it (yet!). Garmin needs to upgrade it algorithms, add or divide a few numbers here and there. You can read more on our smart watch reviews here.

At Refine Naturals™, we believe in a holistic approach for a better sleep. At Refine Naturals™, we believe “You Deserve Better than FINE!”


Scientific References:

  1. Track your sleep with Apple Watch [Internet]. Apple Support [cited 2020 Dec 18];Available from:
  2. What’s sleep score in the Fitbit app? [Internet]. [cited 2020 Nov 26];Available from:
  3. Garmin, subsidiaries GL or its. Garmin fenix® 6 Pro & Sapphire | Multisport Fitness Watch [Internet]. Garmin [cited 2020 Dec 18];Available from:
  4. Oura Ring: Accurate Health Information Accessible to Everyone [Internet]. Oura Ring [cited 2020 Dec 18];Available from:
  5. WHOOP - The World’s Most Powerful Fitness Membership. [Internet]. WHOOP [cited 2020 Dec 18];Available from:
  6. Stone JD, Rentz LE, Forsey J, Ramadan J, Markwald RR, Finomore VS, et al. Evaluations of Commercial Sleep Technologies for Objective Monitoring During Routine Sleeping Conditions. Nat Sci Sleep 2020;12:821–42.
  7. Shcherbina A, Mattsson CM, Waggott D, Salisbury H, Christle JW, Hastie T, et al. Accuracy in Wrist-Worn, Sensor-Based Measurements of Heart Rate and Energy Expenditure in a Diverse Cohort. J Pers Med 2017;7(2):3.
  8. Fitbits, other wearables may not accurately track heart rates in people of color [Internet]. STAT2019 [cited 2020 Dec 18];Available from:
  9. Are the Optical Heart Rate Lights on a Garmin Watch Safe to Expose My Skin To? | Support Center [Internet]. [cited 2020 Dec 18];Available from:
  10. oura-admin. Technology in the Oura Ring [Internet]. Pulse Blog2020 [cited 2020 Dec 18];Available from:
  11. About the Strap LEDs [Internet]. WHOOP2020 [cited 2020 Dec 18];Available from: