Why Your O2Ring Data Has Gaps

Q: Why did the ring lose its reading?

It's loose. This is the most common cause. A loose ring rotates or slides, and the sensor lifts off the skin. See O2Ring sizing. You moved. Rolling over or tucking your hand under the pillow can break contact for a few seconds. Your hands were cold. Less blood flow in the finger means a weaker signal. Pulse oximeter accuracy has more on this. You took it off. A bathroom trip without the ring leaves a gap, or splits the night into two recordings.

Q: Why did the recording stop early?

The battery ran out. Charge it every day, not every few days. The ring came off in your sleep. Check the bed. The memory was full. The ring only holds a handful of nights. Sync every morning so each night is on your phone before the ring runs out of room.

The common reasons an O2Ring recording has missing stretches, how to tell which one you have, and what to change before the next night.

PulseOxTracker Team7 October 2026

You open last night's chart and there's a hole in it. Or the recording stops at 3am. Here's what usually causes that.

What does a gap actually mean?

It means the sensor couldn't get a reading for a while. The ring shines light through your finger, and it needs steady contact to do that. When it loses contact, it has nothing to record.

In the CSV file those moments show up as the number 255. The CSV export guide explains that placeholder.

Why did the ring lose its reading?

It's loose. This is the most common cause. A loose ring rotates or slides, and the sensor lifts off the skin. See O2Ring sizing.
You moved. Rolling over or tucking your hand under the pillow can break contact for a few seconds.
Your hands were cold. Less blood flow in the finger means a weaker signal. Pulse oximeter accuracy has more on this.
You took it off. A bathroom trip without the ring leaves a gap, or splits the night into two recordings.

Why did the recording stop early?

The battery ran out. Charge it every day, not every few days.
The ring came off in your sleep. Check the bed.
The memory was full. The ring only holds a handful of nights. Sync every morning so each night is on your phone before the ring runs out of room.

How do you tell which it was?

Look at the motion line on the chart next to the gap.

Motion right before the gap: you moved and the ring shifted.
No motion, lots of short gaps all night: the fit is loose.
The recording ends and never comes back: battery, or the ring came off.

SpO2 trace with a missing section in the middle, above a motion chart that spikes just before the gap. — A gap in the SpO2 line, with a burst on the motion line just before it.

What should you change?

Change one thing and check the next night.

Move the ring to a finger where it's snug.
Warm your hands before bed if they run cold.
Charge the ring during the day.

If no finger gives you a steady fit, a model with an adjustable finger sensor, like the SleepU or Checkme O2 Max, might suit you better. We compared them in O2Ring vs Checkme O2 Max vs SleepU.

Do gaps ruin the night?

A few short ones don't. A night with an hour missing is a thinner night, so don't compare it against full ones.

Want to check one file quickly? Open the CSV in the free session viewer. In PulseOxTracker you can also tag a night, for example "loose ring", so you know to leave it out when you compare weeks.

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