What a Pulse Oximeter Shows About Your Sleep
What an overnight pulse oximeter records while you sleep, which numbers to look at in the morning, and how to compare your own nights.
You can spend eight hours in bed and still wake up tired. You were asleep, so you didn't see what happened. An overnight pulse oximeter records your blood oxygen and pulse all night, so you can look in the morning.
What does it record?
Two things, every few seconds:
- SpO2. The share of your blood's hemoglobin that's carrying oxygen. See what SpO2 means.
- Pulse rate. Your heart rate in beats per minute.
What will you see in the morning?
- Dips. Short drops in oxygen that recover. Here's what counts as one.
- ODI. How many dips you had per hour. See the ODI post.
- T90. How much of the night you spent below 90%. See what T90 is.
- Your pulse. Whether it settled, and whether it rose and fell in step with the dips. See overnight heart rate.
One low reading on its own is often a cold hand or a loose sensor. We covered that in why your reading might be wrong.
What can't it tell you?
It's not a sleep study. It doesn't record breathing, sleep stages or sound, and it can't tell you whether you have a sleep condition.
- Want to know about noise? That's a different tool. See snoring apps vs oximeters.
- Already on CPAP? See tracking your oxygen alongside CPAP.
What can you test with it?
Pick one habit, change it, and compare your nights:
Change one thing at a time. Single nights vary a lot, so record several before you compare. Here's how many nights to record.
How do you get started?
- Got a device? We have tips for the O2Ring, the SleepU and the Checkme O2 Max.
- Got a recording already? Load one night into the free session viewer. You don't need an account.
- Got numbers but no file? The ODI and T90 calculator works from a count and a recording length.
- Got months of nights in ViHealth? Here's how to move them across.
- Haven't bought one yet? Read whether one is worth it.
In PulseOxTracker you can tag each night with what you did, then compare nights side by side.
When should you see a doctor?
See a doctor if you snore loudly, someone has heard you stop breathing or gasp, or you're exhausted during the day. Do the same if your recordings show repeated dips or long stretches below 90% on several nights. Bring the recordings with you. Here's how to share them.
Not a medical device. Does not diagnose, treat or prevent any condition. Discuss results and changes with a clinician.