Your watch keeps recording after you fall asleep, and those numbers say a lot about recovery. Overnight Vitals are the five health metrics FITIV Pulse reads from your sleep: resting heart rate, heart rate variability (HRV), respiratory rate, blood oxygen (SpO2), and wrist temperature. Each morning FITIV compares last night's values with your own typical range and labels each one Typical, Above, Below, Well Above, or Well Below. Together they show how your body responded to training, stress, and the rest of your day.
What Are Overnight Vitals?
Your body is at its most consistent during sleep. You aren't moving, eating, or talking, so your heart rate, breathing, and temperature settle toward a baseline that reflects your underlying state rather than whatever you were doing a minute ago. That makes overnight readings better for tracking change than daytime spot checks.
FITIV tracks five of them:
| Vital | What it is | Shown as |
|---|---|---|
| Resting heart rate (RHR) | Your average heart rate while asleep | bpm |
| Heart rate variability (HRV) | The variation in time between heartbeats | ms |
| Respiratory rate (RESP) | Breaths per minute while asleep | BrPM |
| Blood oxygen (SpO2) | The share of your blood's hemoglobin carrying oxygen | % |
| Wrist temperature (TEMP) | Skin temperature at the wrist during sleep | °F or °C |
Read them together. A higher resting heart rate after a hard session is normal. A higher resting heart rate alongside lower HRV, faster breathing, and a warmer wrist is a much clearer sign your body is under load.
How FITIV Measures Your Vitals
FITIV reads your vitals from your main sleep of the night. Readings are taken from that sleep session, so a nap or a reading during the day doesn't count toward last night's numbers:
- Resting heart rate is the average of your heart rate samples while asleep, leaving out time you were awake.
- HRV uses FITIV's RMSSD formula by default, calculated from your watch's beat-to-beat heart rate data, or your device's own overnight RMSSD where it provides one. To use the HRV value stored in Apple Health instead, which Apple Watch records as SDNN, go to More tab (•••) > Today Tab > HRV Formula. The HRV Tracking page explains the difference.
- Respiratory rate and blood oxygen are averaged over your sleep by default.
- Wrist temperature is one reading per night, shown as an actual temperature rather than a change from a baseline.
The data comes from Apple Health, Google Health, or Garmin Connect, so you need a device that records these metrics while you sleep. That's usually an Apple Watch, but other wearables that write overnight data to Apple Health also work. If you wear a Fitbit or Pixel Watch, connecting Google Health in FITIV can bring in its overnight data too, depending on what your device records (Fitbit setup). The same goes for a Garmin watch once you connect Garmin in FITIV.
Which vitals you get depends on your device. Apple's own features decide what your watch records: wrist temperature, for example, needs a newer Apple Watch, and Blood Oxygen availability depends on your watch model and where it was purchased (Apple). If a vital isn't recorded, FITIV shows No Data for it and works from the vitals it does have.
Getting Reliable Overnight Readings
The app's own setup steps are short: turn on Sleep Focus, turn off Power Saver mode on your watch, and wear your watch to sleep. A charged watch with a snug fit gives the sensors the best chance of a clean night of data.
What Your Typical Range Means
Every vital is judged against your own history, not a population average. Healthy people vary widely: in a large study of wearable data, 90% of nightly respiratory rate readings from healthy adults fell between about 12 and 19 breaths per minute (Natarajan et al., 2021). A reading that's normal for one person can be unusual for another.
So FITIV builds a typical range for each vital from your recent nights and shows where last night landed:
- Typical means last night was within your usual range.
- Above or Below means it was outside your range.
- Well Above or Well Below means it was further outside.
The status alone doesn't mean good or bad. Lower resting heart rate and higher HRV usually point to better recovery, while a resting heart rate well above your range stands out. Context matters: alcohol, a late meal, a hot bedroom, or a hard workout can each move a night's numbers. A late interval session can leave your resting heart rate at Above the next morning, and the workout explains it. Above after a quiet rest day, with no obvious cause, deserves more attention.
How Overnight Vitals Feed Your Recovery Score
Your vitals are the foundation of FITIV's Recovery score, alongside your Sleep score. In the app's words: lower resting heart rate, higher HRV, and lower respiratory rate all indicate better recovery, and stable or typical blood oxygen and wrist temperature support it.
Each vital moves Recovery in a specific way:
- Resting heart rate and HRV are core inputs, compared with your own typical range.
- Respiratory rate nudges Recovery up when it's lower than usual and down when it's higher.
- Blood oxygen only lowers Recovery, and only when it dips below your usual range.
- Wrist temperature only lowers Recovery, and only when it runs above your usual level. A cooler night isn't penalized.
A missing reading doesn't count against you. If your watch didn't record blood oxygen last night, Recovery simply works from the vitals it has. Recovery then feeds Training Readiness, so your overnight vitals end up shaping the day's training advice.
Where You'll See Your Vitals in FITIV
- Today tab: the Vitals card shows all five metrics with last night's value and status.
- Vitals Summary: tap the card to open the Vitals Summary. Each metric shows your typical range and when it was read, plus 7-day and 30-day averages, recent outliers, and a 30-day chart you can switch between metrics. Tap the question mark for a quick explainer.
- Recovery details: the Contributors list shows each vital and your Sleep score alongside today's Recovery.
- Apple Watch: the Vitals card shows the same five metrics on your wrist.
- Widget: the Vitals Summary widget puts your latest vitals on your iPhone Home Screen.
What Overnight Vitals Can and Can't Tell You
Overnight vitals are good at showing change. If your numbers drift from your usual pattern for a few nights, something has changed: training stress, poor sleep, travel, alcohol, or your body fighting something off. That helps you decide whether to push or back off.
They are not a diagnosis. FITIV is built for fitness tracking and general wellness and isn't designed to diagnose, treat, or monitor any medical condition. FITIV doesn't send notifications about your vitals or try to detect illness. If a reading worries you, or you feel unwell, talk to a healthcare professional. Readings during sleep also depend on fit and sensor contact, so one strange night is more likely a loose strap than a health event. If you also use Apple's Vitals app, our Apple Watch Vitals app guide explains its typical range and outlier notifications.
Frequently Asked Questions
Do I need an Apple Watch for Overnight Vitals?
You need a device that records overnight data to Apple Health, a Fitbit or Pixel Watch connected through Google Health, or a connected Garmin watch. Apple Watch is the most common source. Which of the five vitals you get depends on what your device measures, and any vital it doesn't record shows as No Data.
Do naps count toward my overnight vitals?
No. FITIV reads your vitals from your main sleep of the night, so naps don't change last night's numbers or your Recovery score.
Why does my wrist temperature show as an actual temperature?
FITIV shows wrist temperature as a real value in °F or °C and judges it against your own typical range. Apple's Health app shows the same data as a change from your baseline instead, so the two screens look different but come from the same readings.
Why does one of my vitals show No Data?
Your device may not measure that vital, the feature may be off on your watch, or the watch wasn't worn long enough overnight to record it. Follow the app's setup steps (Sleep Focus on, Power Saver mode off, watch worn to bed) and wear a charged watch with a snug fit.
Does FITIV alert me if my vitals look unusual?
No. FITIV labels each vital against your typical range and factors it into Recovery, but it doesn't send notifications about your vitals or detect illness. If a reading concerns you, check in with a healthcare professional.
