Normal Breathing Rate & Blood Oxygen While Sleeping

While you sleep, your watch quietly records two vital signs most people never think about: how fast you breathe and how much oxygen is in your blood. Both are useful early warning signals, but only if you know what normal looks like.

This guide explains normal ranges for respiratory rate and blood oxygen during sleep, what Apple Watch Vitals shows, and which readings are worth talking to a doctor about.

This article is for general information and is not medical advice. Wearable measurements are not intended for diagnosis. If you have symptoms or concerns, see a doctor.

Normal respiratory rate while sleeping

For healthy adults, a respiratory rate of about 12 to 20 breaths per minute during sleep is generally considered normal. Many people sit in the lower part of that range, and breathing naturally varies across sleep stages: it tends to be slower and steadier in deep sleep and more irregular in REM sleep.

What matters more than the general range is your own typical rate. Respiratory rate is remarkably stable from night to night for most people, which is exactly why a change stands out.

Common reasons for a higher-than-usual overnight respiratory rate:

• an illness starting, such as a cold, flu or other infection
• fever
• alcohol before bed
• sleeping at higher altitude
• stress
• a very hard training day

A rise of a breath or two per minute above your usual level for a night is often nothing. A rise that lasts several nights, especially with other symptoms, is worth paying attention to.

What we see in real Apple Watch data

Published ranges are wide, so we looked at anonymized overnight data from Bodly users with at least a week of Apple Watch readings (data up to September 2026). For each person we took their typical nightly value, then compared people. Blood oxygen is the average of the readings taken while asleep.

Overnight vital	People	Median	Middle 50% of people	8 in 10 people
Respiratory rate	39	15.0 breaths/min	13.5 to 16.6	12.8 to 17.7
Blood oxygen (SpO2)	43	96.0%	95.5% to 96.9%	94.7% to 97.4%

Two things are worth knowing:

• Breathing rate barely moves from night to night. For a typical person it changed by just 0.4 breaths per minute between consecutive nights, and on 9 nights out of 10 by about 1 breath or less. That is why a rise of 2 or more breaths per minute that lasts a few nights stands out, and why your watch can flag it.
• An average in the mid-90s is normal on a wrist sensor. Half of people averaged below 96%, and the lowest personal average was 92%. Wrist readings are noisier than a fingertip clip, so do not read too much into one night's number. Look at your usual level and repeated low readings instead.

These are Bodly users, not a random sample of the population, and the groups are small. This is not a medical reference.

Normal blood oxygen while sleeping

Blood oxygen saturation (SpO2) tells you how much of your blood's hemoglobin is carrying oxygen. For most healthy adults, SpO2 during sleep stays roughly in the mid-to-high 90s, with small, brief dips that are normal.

Overnight SpO2	What it usually means
Around 95% to 100%	Typical for healthy adults
Brief dips into the low 90s	Can be normal, especially if short and occasional
Repeated or sustained readings below about 90%	Not normal. Worth discussing with a doctor

Repeated drops in oxygen during sleep can be a sign of sleep-disordered breathing, such as obstructive sleep apnea, especially if you also snore loudly, wake up gasping, or feel very tired during the day. Only a proper sleep study can diagnose it.

What Apple Watch shows overnight

The Vitals app on Apple Watch shows overnight metrics measured while you sleep:

• heart rate
• respiratory rate
• blood oxygen
• wrist temperature (Series 8 or later and Ultra)
• sleep duration, or heart rate variability on Series 12 and Ultra 4

After you wear your watch to sleep for about seven nights, Vitals establishes a typical range for each metric. If several metrics fall outside that range, you get a notification the next morning with possible factors like alcohol, elevation, medication or illness.

A few practical notes:

• Blood oxygen availability varies. It is not supported on Apple Watch SE, and on some US models blood oxygen is calculated on the paired iPhone and shown in the Health app rather than in Vitals, following Apple's patent dispute with Masimo.
• Apple states that Vitals measurements are not intended for medical use. Treat them as a signal to pay attention, not as a diagnosis.
• Fit matters. A snug fit gives more reliable readings.

How to use your sleep vitals

1. Learn your baseline. Wear your watch to bed consistently for a couple of weeks and note your usual respiratory rate and SpO2.
2. Watch for changes, not single numbers. One unusual night happens. A pattern over several nights is the signal.
3. Look at vitals together. An illness often shows up as a higher respiratory rate, a higher resting heart rate, a lower HRV and a warmer wrist temperature, all at once.
4. Act on the signal. A cluster of outliers is a good reason to rest, hydrate and skip hard training. Persistent changes or symptoms are a reason to see a doctor.

Your overnight vitals also shape how recovered you are. Bodly reads your Apple Health data, including overnight heart rate, HRV and sleep, and turns it into a daily recovery and sleep score measured against your own baseline, so you can see at a glance when your body is under strain.

When to see a doctor

Talk to a doctor if you notice:

• blood oxygen repeatedly or persistently below about 90% during sleep
• loud snoring, gasping or choking during sleep, or pauses in breathing noticed by a partner
• a respiratory rate that stays well above your usual for several nights, especially with fever, cough or shortness of breath
• severe daytime sleepiness despite enough time in bed

Bottom line

A normal respiratory rate during sleep is about 12 to 20 breaths per minute, and normal blood oxygen stays roughly in the mid-to-high 90s with brief small dips. Your watch is most useful for spotting changes from your own baseline, which often show up before you feel unwell.

Wear your watch to bed consistently, learn your typical ranges, and treat persistent changes or symptoms as a reason to rest or see a doctor.

Keep reading

• Apple Watch resting heart rate: what is normal and how accurate it is.
• Good HRV by age: what a normal heart rate variability looks like for you.
• Does Apple Watch track stress?: what your watch can tell you about stress.

Sources

• Track your overnight and daytime vitals with Apple Watch (Apple Support)
• An update on Blood Oxygen for Apple Watch in the U.S. (Apple Newsroom, 2025)
• Normal oxygen levels while sleeping (Sleep Foundation)
• Respiratory rate while sleeping (Sleep Foundation)