Respiratory Rate During Sleep: What Apple Watch Records

Once you are asleep, your breathing settles into its own rhythm. For many people the overnight rate varies only a little from night to night (a large wearable study found within-person variation of a few per cent, somewhat more in older adults), and Apple's Vitals app compares each night with your own typical range. This guide covers what Apple Watch records, what is typical for adults, and how My Bio Age summarises a night.

What Apple Watch measures

Respiratory rate is the number of breaths you take per minute. Apple's HealthKit documentation describes it as a quantity counted over time and notes that Apple Watch records the samples automatically. With sleep tracking turned on, Apple's sleep guide explains that the Health app can show your respiratory rate alongside the time you spent asleep.

The Vitals app on Apple Watch gathers several overnight measurements, including heart rate, respiratory rate, blood oxygen and wrist temperature. According to Apple's Vitals app guide, it needs Track Sleep with Apple Watch and Sleep Focus turned on, and about 7 nights of wearing the watch to bed before it can establish your typical range. A loose fit can make readings less accurate, and Apple states that Vitals measurements are not intended for medical use.

Typical values and your own range

MedlinePlus gives 12 to 18 breaths per minute as the normal resting range for a healthy adult, and points out that what is normal differs from person to person, with factors such as age and general health. That is a general vital-sign range, not one measured during sleep. For overnight readings, the wearable study above, which used Fitbit devices, found that 90% of healthy adults' nightly values fell between about 11.8 and 19.2 breaths per minute. My Bio Age's respiratory rate detail view shows a slightly wider guide of 12 to 20 breaths per minute, a reminder that reference ranges differ between sources.

A population range is a broad reference, not a personal target. Vitals instead builds a typical range for you, and Apple lists medication, elevation, alcohol and illness among the factors that can shift your overnight measurements. A clear change from your usual nights tells you more than any single value.

How My Bio Age summarises it

• One value per night. My Bio Age reads respiratory-rate readings from Apple Health and groups those that start within the same 9 pm to 9 pm window, labelling the night by the day you wake up. The night's value is their median, so a few unusual samples move it less than they would an average.
• A weekly average. For each complete Monday-to-Sunday week, the app averages the nightly values. Five or more recorded nights give full confidence; fewer nights count for less. If a week has no recorded nights, the app reuses your most recent night from the week before, at lower confidence.
• A card in Overview. The Respiratory Rate card shows your latest complete week's average with a small trend line, and its detail view charts your history.

Its role in the app

• An Index input, read as context. Respiratory rate is one of the 12 core metrics listed behind the weekly MyBioAge Index™, with one of the smaller weights. Read it as context alongside heavier inputs such as VO₂max, HRV and sleep.
• Not part of the daily scores. Recovery, Training Load, Stress Resilience and Circadian Alignment are all calculated without it.
• A data checklist item. When the Index shows its data checklist, respiratory rate looks for about four recorded nights a week, or six in the past 10 days, and when nights are missing the checklist says how many more it needs. Missing respiratory data won't hold back the Index on its own, unlike missing VO₂max, HRV or sleep regularity data.
• An AI Coach topic. You can choose Respiratory Rate when asking the on-device coach about a metric.

In My Bio Age 1.0.23, now in development, the weekly MyBioAge Index™ starts comparing each week's average respiratory rate with a fixed population reference. A sustained higher weekly rate counts as slightly older and a lower one earns only limited credit, and the effect on the Index is small and capped. It is still best read as context alongside the heavier inputs.

Reading a change calmly

1. Look across several nights. A single night says little on its own. Compare the week with the weeks before it.
2. Note what was different. Alcohol, a trip to higher elevation, a cold or a new medication can all sit behind a run of unusual nights.
3. Check for missing nights. A watch left on the charger leaves a gap, so the weekly average rests on fewer nights (or, for a week with none, on a carried-over night), and a loose fit can make the readings you do get less reliable.
4. Read it with other overnight signals. My Bio Age also summarises wrist temperature and blood oxygen by night, so you can review them side by side.

If you have difficulty breathing, get medical help promptly rather than checking a wearable. If a change in your overnight rate persists alongside symptoms, such as feeling unwell or unusually breathless, talk to a doctor or another qualified clinician.

Overnight respiratory rate is also not a sleep apnea screen. The NHLBI lists signs such as loud snoring, gasping for air, breathing that stops and starts, and daytime sleepiness, and notes that a sleep study may be needed for a diagnosis. If you or a partner notice these signs, speak to a healthcare provider, whatever your numbers show.

Putting it together

Overnight respiratory rate is most useful as one part of the wider picture of your nights. For the rest of that picture, read our sleep duration guide and these sleep habits for HRV and resting heart rate. Our Methods & Sources page explains how the Index is built.

Download My Bio Age free on the App Store to review the respiratory-rate readings in Apple Health alongside sleep and other nightly signals. The iPhone app is completely free, with no in-app purchases, subscription or account required. Your health data stays private on your iPhone, including when you use the fully on-device AI Coach.

My Bio Age processes the health data it uses on your iPhone and provides general wellness information, not medical advice. It does not diagnose breathing or sleep conditions, and a change in any reading is a prompt to look at your routine, not a reason to change your treatment.