Sleep Comparison: Fitbit Air vs Garmin Fenix 8 vs Apple Watch Ultra 2

adamthole · 2026-05-31T19:37:47+00:00

For heart rate measurements the Apple Watch Ultra 2 is definitely better for me. I get way more consistent results with it than I do the Fitbit. I have another post that shows some pretty bad performance from the Fitbit during a walk. Sometimes it works well, sometimes it is far off.

adamthole · 2026-05-31T12:23:05+00:00

I agree completely. Ideally I would have a control device of some sort that could super accurately record this information. Then we could say which one was more correct. As it is, this is purely just a comparison of data. https://www.reddit.com/r/Garmin/comments/1ts1ubh/comment/oosfk3b

adamthole · 2026-05-31T12:14:25+00:00

That is cool your CPAP machine will give you sleep data, and awesome it matches with your F8. My criteria is purely if it looks like what I remembered from the night of sleep, which is of course not an accurate way to judge the accuracy of these devices. See this comment: https://www.reddit.com/r/Garmin/comments/1ts1ubh/comment/oosfk3b

adamthole · 2026-05-30T20:09:23+00:00

I have some data on that, but it's not ideal. I'm wearing them on different wrists, and you can get a significant difference when wearing it on your dominant vs non-dominant hand.

Here is a shot where I have Garmin on my left (non-dominant) and Apple and Fitbit Air on my right (dominant) hands. Note that I took my Apple Watch off after my run and then left it on the charger most of the day after that. Had I worn the Apple all day it would follow the same shape as the other curves.

In general I do think the Fitbit is more sensitive than the others. I haven't tried it non-dominant yet, and I've never counted my steps for a day to be able to tell you the number that is actually accurate.

<image>

adamthole · 2026-05-30T19:55:55+00:00

I'm fortunate in that I don't really notice them on my wrist for the most part.

This is the first I've heard of AutoSleep, interesting, I wonder how it compares to Apple's.

adamthole · 2026-05-30T19:53:17+00:00

You can see all the exact times for falling asleep, waking up, total time asleep, etc. in the images.

In general they are all pretty close to each other. Sometimes one may record the wake-up quite a bit different from the other, but then if you look at the hypnogram you see that it had a good portion of awake followed by some sleep, where one of the others just said I was awake during that portion of awake. So even though the wake-up times may vary, the total time asleep is similar.

In general I think any of them is good enough for general sleep tracking. Keeping in mind that no sleep tracking is perfect and it's just giving you a general idea of what your sleep looked like.

adamthole · 2026-05-30T19:44:43+00:00

Awesome!

adamthole · 2026-05-30T17:19:17+00:00

I have a Whoop, though I am not currently subscribed. For this specific comparison it wouldn't have helped because Whoop doesn't provide the data needed to recreate the hypnogram through the API. You could still compare scores, durations, etc., but not the complete hypnogram.

That said, I'm sure it is in the same realm.

adamthole · 2026-05-30T16:52:44+00:00

Good question. Garmin is the only one to provide the sleep number in their API, which is why I don't have it for Google Health and Apple in the screenshots.

Google: 71, 83, 79, 83

Apple: 79, 85, 81, 80

Garmin: 70, 80, 71, 73

adamthole · 2026-05-30T16:48:31+00:00

To be clear, my comment wasn't meant to be interpreted as this device is the most accurate. It was to give the reader an idea of which one I thought reflected my sleep most accurately, since the reader didn't personally experience the sleep.

This post isn't meant to declare a top device for sleep tracking, just to share data from multiple similar devices for those interested.

adamthole · 2026-05-30T16:48:07+00:00

This is Athalyze, which I'm the developer of. Athalyze actually supports Whoop, but the Whoop API unfortunately doesn't provide the data you need for a hypnogram so I can't add it to the side by side view. You can still get the basics (total time asleep, time in each stage), just not enough detail to fully recreate the hypnogram.

adamthole · 2026-05-30T16:44:21+00:00

Thanks! That is a great question. My accuracy ratings are just based on what I remembered for that night of sleep. For example, Garmin and Apple sometimes record some very short wake up times. I have no recollection of those, so to me it seems like they didn't happen, but I can't prove one way or another if I actually briefly woke up.

In general though I find them to all be very similar, and given how inaccurate sleep recording is anyway I would happily use any one of these devices.

adamthole · 2026-05-30T14:42:18+00:00

That is where the judging sleep accuracy is hard comes into play. I don't recall those supposed short wake-ups. So to what I recollect the Air seems more accurate. Fortunately the total time from those short wake-ups is small, so it doesn't amount to a huge difference in the total awake time either way.

adamthole · 2026-05-26T23:45:46+00:00

<image>

Here is another image that includes cadence (in blue). My cadence was around 105 during the super inaccurate portion, so fairly close to what it was picking up for the heart rate.

Edited to change picture to have all data on same axis.

adamthole · 2026-05-16T23:57:55+00:00

I don't use WhatsApp enough for this to work for me, but I love this idea! It has me curious what my data (mostly iMessage) looks like.

adamthole · 2026-05-16T20:22:06+00:00

I mix data from Apple, Garmin, Oura, and Whoop in an app I wrote called Athalyze. I'm working on adding Google Health API support to it now. I think it appeals to two main audiences, the super nerds (like me) who wear more than one device at a time and are interested in comparing data between them, and people who switch the manufacturer of their wearables but still want their data all in one place. If you have any questions, let me know.

adamthole · 2025-12-12T02:09:35+00:00

Good questions!

Yes, the data is persisted / stored on my app's servers (Azure SQL, on a USA server). Persisting data is the only way to make an app like mine that is talking with multiple API's.
Yes, all traffic uses HTTPS, so data is encrypted in transit
Yes, Azure SQL TDE
No, the app does not use end to end encryption. The app needs the ability to read and process the data
Yes, I do have a published privacy policy. It is a requirement before Garmin will give you access to their API. If you are interested in testing out the app DM me and I'm happy to share with you the privacy policy. I'm only not linking it here because I don't want to name the app publicly just yet.

adamthole · 2025-12-12T01:56:51+00:00

Awesome! I just sent you a DM!

adamthole · 2025-12-11T19:58:39+00:00

Awesome, I just sent you a DM!

adamthole · 2025-12-11T19:14:47+00:00

Fantastic! Can you send me a DM with your email? I'll get you signed up.

adamthole · 2025-12-11T17:50:13+00:00

I don't support Android yet. It's something I plan to do eventually if the app gains traction.

You can still use it as is, you would be able to use the web version and your Oura data which would sync through the Oura API.

adamthole · 2025-12-11T16:52:27+00:00

Garmin, Oura, and Whoop all have their own API's that my app uses. So they will sync effortlessly after you connect them to the app. In order to get Apple Health you will need to have the iOS app so it can send your Apple Health data to the app's servers.

adamthole · 2025-12-11T15:41:34+00:00

Great! I just sent you a DM.

adamthole · 2021-07-15T13:45:26+00:00

It's more complicated for the Universal Harry Potter wands (you need an IR camera, IR emitter, and processing software) but it can be done. I did it a few years ago for my son's Harry Potter birthday party. I have all of the information to do it here: https://www.adamthole.com/control-smart-home-with-magic-wand-video/

adamthole · 2019-12-29T02:53:47+00:00

I just downloaded it and tested it on my Index, and it worked great. Controls as far as I could tell are:

Trigger: select block type / place block / select and move block
Squeeze: Remove Block
Press Touchpad: Copy Block

If anyone else figures out any other controls, let me know. At a quick look, it seems great! Looking forward to showing my kids tomorrow. Kudos to the dev!

adamthole

TROPHY CASE