Coming soon on iPhone
Early SignalYour nights already knowwhen to take a rest day
Early Signal measures personal variations in your overnight biometric baselines and suggests low-risk rest actions.
We'll email at launch. The warning stays free.
Today
Slightly off
Small changes vs your usual pattern
Skip hard training
Keep movement light until signals settle
Drink more fluids than usual
Water or electrolyte drinks — little and often
Get to bed early
Aim for an earlier bedtime tonight
Wrist
Lead
Breathing
Lead
HRV
Support
Resting
Support
Sleep
Context
- iPhone, iOS 17+
- Apple Watch with overnight HRV
- Series 8+ for wrist temperature
- Wear it overnight
Medical disclaimer
GetEarlySignal is a wellness tracking and rest-day support tool. It does not provide medical diagnoses, treatment plans, clinical assessments, or healthcare advice. The app does not replace professional medical care or emergency healthcare services.
What is Early Signal?
Early Signal is a consumer wellness tool for iPhone and Apple Watch. It measures personal variations in overnight biometric baselines—wrist temperature, breathing rate, heart rate variability (HRV), resting heart rate (RHR), and sleep—to suggest low-risk rest actions. It does not diagnose or treat disease and is not medical advice.
For people who already have a Watch
You don't need another gadget, a dashboard to stare at, or an account
You already wear a Watch
No new ring or strap — Early Signal uses nights already in Apple Health
You don't want another dashboard
A rare heads-up, not charts to stare at every morning
You want it private
On your iPhone by default, no account
Temperature and breathing lead
Strain differentiators first, heart metrics as support, sleep as context. If your Watch has never recorded wrist temperature, Temp is omitted from the ring. Missing data never looks “in range.”
Lead
Wrist temperature
Series 8+ overnight rise vs you
Lead
Breathing rate
Series 3+ respiratory shift
Support
HRV
Overnight variability drop
Support
Resting heart rate
Personal RHR climb
Context
Sleep
Restorative overnight context
How wearable data is read
GetEarlySignal reads overnight biometric samples that Apple Watch has written to Apple Health. The inputs are sleeping wrist temperature, respiratory rate, heart rate variability (HRV), resting heart rate (RHR), and sleep (asleep time, used as context). Scoring looks for personal deviations from your own baseline, such as a drop in HRV together with a rise in overnight respiratory rate or wrist temperature. Those deviations are wellness markers used to suggest a rest day. They are not a disease detection, a clinical assessment, or a prediction that you will feel unwell. Blood oxygen (SpO2) is not an input.
Three steps, no new hardware
Early Signal reads nights already in Apple Health, compares them only to you, and suggests a rest day when the pattern is off. No new ring, and no need to learn what HRV means.
01
Overnight Health sync
The app reads native overnight biometric samples from Apple Health on your iPhone, including data from Apple Watch. Access is read-only. Wrist temperature, respiratory rate, HRV, resting heart rate, and sleep stay on the device.
02
Personal baseline
The algorithm maps your individual usual pattern from your own nights, using a median and a median absolute deviation. It does not compare you with population averages or age-group norms.
03
Early rest-day heads-up
If several signals move past your usual variance together, or wrist temperature stays elevated versus you, the app shows Slightly off or Off from usual and suggests low-risk actions such as rest, extra fluids, and an earlier bedtime. Off from usual pushes are capped at one every 3 days.
From a status to a rest action
When GetEarlySignal shows Slightly off or Off from usual, Today turns that status into a short list of recovery steps: skip hard training, drink more fluids than usual, and get to bed earlier. You can log context such as a hard workout, travel, alcohol, or a short night you chose. The result stays a wellness suggestion on your iPhone.
More on the how it works and science pages How it works · Science
A morning status you can act on
Today, Trends, and a widget — not another biometric dashboard
Trends
Wrist temp
Breathing
HRV
Lead signals first, compared only to you
Today
Off from usual
Several signals moved together
Skip hard training
Give your body a recovery day.
Drink more fluids than usual
Water or electrolyte drinks — little and often
Home screen
Early Signal
Slightly off
Status at a glance
Not another place to check the numbers
Apple already has the nights. Early Signal turns them into a status — a complement, not a replacement
Activity rings
Close the rings for the day
Overnight strain, compared to you
Apple Health
Last night's numbers and charts
A morning status and a rare alert you can act on
Another ring or strap
New hardware and a membership
The Watch you already wear
Private by design
Your biometric data is personal, so the app never needs a cloud account
On-device by default
Raw health data stays on your iPhone — no account
Read-only Apple Health
We read wrist temperature, respiratory rate, HRV, resting heart rate, sleep, and workouts. We don't write to Apple Health or share samples
No ads, no data sale
We don't sell health data, use it for ads, or train a general-purpose model on it
On-device computing. Biometric logs are stored on your iPhone with iOS data protection. We maintain strict data silos. Your personal health metrics, biometric logs, and tracking data stay on your device and are not used to train external AI or language models.
What you get
Clear morning status, rare alerts, and widgets. The warning stays free — Pro adds depth, and we never show it on an Off from usual morning
- Morning status: Typical, Slightly off, or Off from usual
- Wrist temperature and breathing rate as lead signals — Temp omitted if your Watch has never recorded it
- Plain-language reasons when signals move together
- Trends with wrist temperature and breathing first, then HRV, resting heart rate, and sleep
- Home and lock-screen widgets for status at a glance
- Optional check-ins, alert pause, and delete-all-data in Settings
Requires an Apple Watch that records overnight HRV. Wrist temperature needs Series 8 or later; respiratory rate works from Series 3. Works offline. The warning stays free — Pro optional.
Common questions
Alerts, Learning mode, widgets, and what a status does — and doesn't — mean
Can an Apple Watch detect early signals of sickness?
How does GetEarlySignal map my heart rate variability (HRV)?
Is my wearable health data secure in the GetEarlySignal app?
Is Early Signal a medical device?
Take a rest day before you feel exhausted
Leave your email. We'll tell you when it's on the App Store — a rare heads-up, not another dashboard