Do Cheap Pulse Oximeters Work Overnight?

You can buy a fingertip pulse oximeter online for the price of a takeaway. It'll give you a blood oxygen (SpO2) number in a few seconds.

Can you wear it to bed and get a night's recording? Usually not.

Why doesn't a basic clip work overnight?

A basic clip is made for spot checks. That causes three problems at night:

• No memory. Most show the current number and store nothing. You'd have to be awake to read it.
• Auto power-off. Many switch off after a short time, or when the signal drops.
• The clip itself. A spring clip pinches after an hour and comes off when you roll over.

A few low-cost clips do have memory or Bluetooth. Read the listing closely, because "Bluetooth" sometimes means a live display on your phone and not a saved recording.

How do the options compare?

What should you look for on the listing?

If you want to try a budget model overnight, check that it says all of these:

• It records continuously for at least 8 hours.
• It stores the recording on the device, so your phone doesn't have to stay connected.
• You can export the data as a file.
• The battery lasts a full night with recording on.

If the listing doesn't say, assume it doesn't. The longer checklist is in what to check before buying an oximeter.

Is a cheap one accurate enough?

Some are and some aren't, and you can't tell which from the listing.

One study tested six low-cost fingertip oximeters against blood samples from 22 healthy adults.

• Two of the six met the international accuracy standard across the whole range tested.
• Four showed large errors when oxygen was below 80%.
• Three showed large errors between 80% and 90%.

So in that study, the errors were largest when oxygen was low. That study is from 2016, and the models on sale now are different.

Many consumer oximeters are sold for general wellness or sport, not for medical use. That includes pricier ones: Wellue's listing says the O2Ring is for general wellness use. Check what the listing says the device is intended for.

Is overnight harder than a spot check?

Yes, for any oximeter.

• Your hand cools down.
• You move.
• The sensor shifts.

A clip that slides around will add false dips. Why a reading might be wrong covers what to watch for. Readings can also run high on darker skin, which we cover in pulse oximeters and skin tone.

Can you just check a few times in the night?

You can, but it won't tell you much.

• You have to wake up to do it, and oxygen dips happen while you're asleep.
• A dip can last under a minute, so you'd need luck to catch one.
• You end up with a handful of numbers and no way to count dips or compare nights.

That's why overnight devices record every few seconds. See what counts as an oxygen dip.

When is a cheap clip the right choice?

• You want a quick reading while you're awake and still.
• You want something small for a trip. A clip is handy for checking your oxygen on a flight or at altitude.
• You're curious and don't want to spend much.

For those, a basic clip does the job.

How much more is an overnight device?

Quite a bit. At the time of writing, Wellue's own store listed its three overnight models between about $150 and $230, depending on the model and discount. Check the listing, because prices change.

For that you get:

• A sensor shaped to stay on while you sleep.
• Memory for several nights on the device.
• A file export.

Whether that's worth it depends on what you'll do with the data. Read is an overnight pulse oximeter worth it? before spending anything.

So what should you buy?

• You only want a daytime spot check: a cheap clip does the job.
• You want to see your whole night: get a device built for it, like a ring or a wrist unit with a soft finger sensor. Compare the shapes in ring vs fingertip vs wrist.
• You already have a smartwatch: see what it records first, in smartwatch SpO2 vs a pulse oximeter.
• You mainly want to know about snoring: a phone app may be enough. See snoring apps vs oximeters.

PulseOxTracker works with the Wellue O2Ring, SleepU and Checkme O2 Max. It doesn't sync with generic fingertip clips.

A home oximeter of any price is not a sleep study. If you snore loudly, stop breathing or gasp in your sleep, or you're exhausted during the day, see a doctor.

Not a medical device. Does not diagnose, treat or prevent any condition. Discuss results and changes with a clinician.

References

1. Lipnick MS, Feiner JR, Au P, Bernstein M, Bickler PE. The accuracy of 6 inexpensive pulse oximeters not cleared by the Food and Drug Administration: the possible global public health implications. Anesthesia & Analgesia. 2016;123(2):338-345. doi:10.1213/ANE.0000000000001300
2. Wellue. O2Ring product listing. getwellue.com. Checked October 2026.