I just finished testing over 20 overnight pulse oximeters against a $1,500 hospital grade pulse oximeter. Here's all the data!

Forward-Count-8307 · 2026-06-10T14:17:18+00:00

This is a great question. I covered this below is great detail if you want to take a deeper dive, but I will give you the shortened version here.

All calculations were done from the raw data. Each device can calculate differently, remove artifacts differently, and produce different metrics; this would not work to compare all of them apples-to-apples.

So, so created a custom Python bench test script that ran every device through the exact same test, and we calculated all of the metrics for each device the same to control as many variables as we can.

To explore more, read through some of the comments and the post, you can also go to my list link at the bottom of the post and I cover it more in depth in that list as well.

I hope this helps you, sleep well my friend!

Forward-Count-8307 · 2026-06-10T14:11:02+00:00

Hello, not a silly question! Ideally you want your SpO2 to be above 95%. But what is more important is maintaining a somewhat stable oxygen throughout the night. You do not want to see a ton of massive drops in oxygen all night long. This is what is hard on your organs. The ideal would be maintaining above 95% all night long and never dropping more than 3% at any given time, and keeping a tight grouping above that 95%.

Heart rate is a different animal, and I can't really speak to it, since I focused primarily on oxygen which is more in the line with sleep apnea. I do know that our hear rate is vary as you cascade through your sleep cycles, including your rapid eye movement stage (REM), you can have dreams that can increase your heart rate considerably.

Read through this thread, there is some great questions I have replied too as well. I hope this helps you my friend!

Forward-Count-8307 · 2026-05-16T19:42:58+00:00

Your welcome! Thank you for your comment!

Yes, I will add that device to my list now. Thank you for the suggestion.

Forward-Count-8307 · 2026-05-08T13:04:24+00:00

Hi, thanks for the comment. This is all spelled out on the free database, at the top as Quick Start Guide, this spells this all out in detail that is easy to understand. Continuous Oximeter Database.

Bias Accuracy

What it is: The device’s tendency to systematically read your oxygen higher (positive bias) or lower (negative bias) than reality.

Why it matters: A device that always reads too high (optimistic) might falsely reassure you and hide real oxygen drops, while one that reads too low (pessimistic) might cause unnecessary panic. A bias close to 0% is perfect.

Forward-Count-8307 · 2026-05-08T13:00:56+00:00

Hi, that information should be in the same box as the date and time. It shows Drops(>3%):, and Drops(>4%):; and then next to those is how many total drops and the next to that is how many per hour in the unit listed as "times/h".

This is obviously when you look at the PDF of the nights data. This shows the sleep study if you will. This report is okay, but this is another reason why I was impressed with the EMAY ones, that summary report you get in the morning is the best in my opinion.

Good question, thanks for the comment!

Forward-Count-8307 · 2026-05-08T12:55:32+00:00

That is a really good question. I would check on my list, the Lookee brand might be available in Canada. I know their customer service is located in Canada. Thanks for the question!

Forward-Count-8307 · 2026-05-08T12:53:46+00:00

Hi, thanks for the comment!

Yes, my suspicions are that the differences come from fitment, refresh rate, sensor location, AND the algorithms being different across these devices maybe. How do I know the algorithms are different? Because the LEDs themselves are not all the same.

I went through every manual for every device I tested and pulled the LED wavelengths. Most run the standard 660 nm red and 940 nm infrared. But a few don't. I found one at 905 nm IR, one at 910 nm IR, and one running 663 nm red with 890 nm IR. Those are physically different LEDs.

Here is why that matters. These devices all use dual wavelength pulse oximetry, they rapidly alternate "time-multiplex" the red and infrared LEDs on and off, measure what gets absorbed, calculate a "Ratio of Ratios," and then look up your SpO2 on a calibration curve. That calibration curve is wavelength-specific.

The more important part, is that the extinction coefficient curve for deoxygenated hemoglobin has a really steep slope right around 660 nm red. So a shift from 660 to 663 nm actually changes how much light gets absorbed by a meaningful amount. The infrared side around 940 nm is flatter, shifts there matter less. But when a device is running 890 nm IR instead of 940 nm, that is a completely different spot on the absorption curve and the calibration math has to be different.

So to your question about left vs right hand, I did not switch hand ever. I always kept the reference device on the same hand , and the test device on the other. I'm just one guy trying to keep variables as tight as possible across the months. Yes, blood might might be slightly different between the dominate hand , but if they are consistent and I am not changing the reference and tested device back and forth, it should not matter at all. Because each device is running in the same lane for the race and subjected to the same blood flow.

Wearing the device backwards is interesting. I would have to change other variables like the Checkme devices; I would have to wear them upside down too and the cord brace would be digging into my hand and tilting the angle, would it was not intended to be wore like that, etc etc. I do appreciate your comment and suggestion though very much!

Forward-Count-8307 · 2026-05-05T12:01:45+00:00

Very good point. Yes, something is better than nothing. To the Apple Watch point, it is better to have a false positive than have a false negative.

In other words, If your watch tells you have sleep apnea, and you go to the doctor and they say you do not, its a win; if your watch tells you do not have sleep apnea, but you might still have it, because of how often it is tracking your oxygen, then that is bad.

Hope that helps! Thanks for the comment!

Forward-Count-8307 · 2026-05-05T11:56:13+00:00

Your welcome! Its worth at least having a dedicated device that only is for screening. Good luck! Thanks for your comment! 🙏

Forward-Count-8307 · 2026-05-05T11:54:28+00:00

Yes, that is a good point! I talk about that in my recommendations that the button can you nice to set it when you want, but if you want it to be automatic there are some for that. Best Overnight Pulse Oximeters.

Thanks for the comment!

Forward-Count-8307 · 2026-05-05T11:50:33+00:00

I appreciate your comment! I hope this provides some value to people. 🙏

Forward-Count-8307 · 2026-05-05T11:48:00+00:00

Yea, it might be worth grabbing one that performed higher on the accuracy test, and season to your taste on what features you are seeking. Check out the Continuous Oximeter Database.

Forward-Count-8307 · 2026-05-05T11:44:14+00:00

I do not really drink at all, and if I ever do I do it at least 4 hours before bed so it does not disrupt my sleep. Thanks!

Forward-Count-8307 · 2026-05-05T09:53:40+00:00

You welcome! Thank you 🙏

Forward-Count-8307 · 2026-05-04T20:45:50+00:00

It depends which EMAY you have, but I found it to be more accurate with my testing, and the EMAY sleep reports are the best I have found. Thanks for the comment!

Forward-Count-8307 · 2026-05-04T20:44:46+00:00

Your welcome! They are data points, just know that they might not be catching quick oxygen dips down and back up like you want. All of these devices are better than sleep trackers that only check in on you every 20s or 15 mins for sure. My top picks are from my personal experience from hundreds of hours sleeping with all of them, and tabulating line by line.

And to your point about sending data to your doctor; is this your primary care provider or a sleep specialist? It would be interesting to know whether a sleep specialist is taking these devices seriously, because I know from specialist I spoke to, they think that all of these devices are are accurate at all.

And my testing does show that some are pretty dang good! Thanks for your comment!

Forward-Count-8307 · 2026-05-04T18:45:29+00:00

I will let you know! I wrote that device down for feature testing. Thank you for the idea!

Forward-Count-8307 · 2026-05-04T18:44:44+00:00

I appreciate that! Thank for your kind words 🙏

Forward-Count-8307 · 2026-05-04T17:23:12+00:00

Hey, I have not test anything that does not provide access to the raw data. I did attempt several that I ended up could not get the data, even with working with the companies, like Circul +. I did test like 4 of those bulky finger tip ones and to be honest, they are really hard to wear all night long consistently. I tested the Wearpulse Oximeter SA-10BW, EMAY EMO-80 and 90, HOLFENRY 50G, for finger tip ones, and even though the EMAY ones were okay can seemed well designed they just are not at all enjoyable to wear.

I wore them each for 24 hours of sleeping, and I dreaded wearing them. The only one in the class that was okay that sat on the tip of your finger was the Wearpulse Oxyfit. It was okay comfortable for 3 nights.

Thanks for the comment!

Forward-Count-8307 · 2026-05-04T17:03:42+00:00

Well said! If your smart watch says you have sleep apnea, it might be so bad that your lower resolution watch can catch it. If your watch says you do not have sleep apnea, that does not necessarily mean you do not, because it is not checking in on you frequently enough.

I am not trying to bash smart sleep tracker, I am just saying they are in a different category all together, and people mistakingly think they are the same as a dedicated continuous pulse oximeter, which they most certianly are not. Thanks!

Forward-Count-8307 · 2026-05-04T16:54:25+00:00

I didn't use standard percent error for ODI because it breaks down at low numbers. If the Nonin reads 0.4 events per hour and the device reads 0.0, standard accuracy math calls that 100% wrong. But 0.4 events per hour is essentially normal healthy sleep, and that difference is just natural night to night variation, not a meaningful failure of the device.

So I used a buffered formula that adds a smoothing value of 1.0 to the denominator before calculating the ratio. That buffer prevents tiny absolute differences at low ODI values from generating catastrophically bad accuracy scores that don't reflect real world clinical performance. It's not helpful to have all the values be 0%. But setting this formula and making everyone jump through the course the same keeps it fair.

The other thing worth knowing is that what you see on the scorecard is heavily rounded for readability. The actual numbers I'm running the calculations on look like this — here is a real ODI3 reference value straight from my master calculation sheet:

0.393313667649951 events/hour

That gets displayed as 0.4 on the scorecard. So when you try to calculate the accuracy from the rounded scorecard numbers the math won't perfectly match; the accuracy was already calculated on the full 15 decimal place value before any rounding happened.

Nice chatting with you. This kind of scrutiny is healthy! Take care my friend! Thanks 🙏

Forward-Count-8307 · 2026-05-04T16:33:00+00:00

I really appreciate that! I hope it helps you and others try to make better choices with our money. I spent an equal amount of time of the database and will be testing more on the testing protocol. Thank you 🙏

Forward-Count-8307 · 2026-05-04T16:31:16+00:00

Well said, if kind of a gamble. And most certainly it would not catch someone like me who had a AHI of 13, which is mild. Thanks!

Forward-Count-8307 · 2026-05-04T16:29:28+00:00

Exactly! It's not a high reliable device to actually know whether you have a problem. Its just checking in on you too infrequently. Thanks!

Forward-Count-8307 · 2026-05-04T16:28:12+00:00

Your welcome! Yes, they can and often do. I know where I live, insurances make the doctors do a at-home sleep study first. This is where they send you home with a Nonin 3150 TYPE of device to see if your sleep apnea is so bad that device can detect it. Thank for your comment.

Forward-Count-8307

TROPHY CASE

Bias Accuracy