Frequently Asked Questions

Stress uses short labels that fit cards and the watch face. The meaning is the same in every language; only the compact name changes.

• English: HRV / RHR
• Simplified Chinese: 心率变异性 / 静息心率
• Traditional Chinese: 心率變異性 / 靜息心率
• Japanese: 心拍変動 / 安静時心拍
• Korean: 심박변이 / 안정시 심박
• German: HRV / Ruhepuls
• French: VFC / FC repos
• Spanish: VFC / FC reposo
• Italian: HRV / FC riposo
• Brazilian Portuguese: VFC / FC repouso
• Turkish: HRV / İstirahat nabzı
• Units: bpm and ms stay Latin in every language.

HRV (heart rate variability) is the tiny timing difference between heartbeats, read from Apple Health as SDNN in milliseconds. RHR (resting heart rate) is your typical resting pulse in bpm. Stress uses both, with HRV as the main signal, to build your personal baseline—not as a medical lab report.

Yes. They are the same HealthKit metric: heart rate variability (SDNN). English UI uses the short label HRV so cards and complications stay readable; Simplified Chinese spells it out as 心率变异性. Traditional Chinese, Japanese, Korean, and other languages each use their own compact name. Units stay ms. Nothing in the calculation changes when you switch language—only the label on screen.

No. Apple Watch does not include a stress sensor, and Apple Health does not provide a system stress score that third-party apps can read. Stress estimates physiological load on your iPhone from HealthKit samples the Watch already collects—mainly HRV, plus heart rate in Real-time mode, compared with your personal baseline.

That is why you still need the Stress app (and Health access) even if you already wear an Apple Watch. Other metrics you may see in Stress, such as sleep, steps, water, or daylight, are shown for context. They are not a hidden Apple “stress API.”

No account, and no Stress cloud for health data. With your permission, Stress reads HealthKit on this device and calculates stress, baseline, and trends on-device. Raw samples stay in Apple Health. Computed records are stored locally with SwiftData. They are not uploaded to Stress servers, not used for ads, and the app does not include a third-party analytics SDK.

Optional iCloud Key-Value Store syncs preferences only—theme, language, daily goals, card layout, calculation mode. It does not sync HRV samples or stress history. iPhone and Apple Watch exchange baseline statistics over WatchConnectivity on your own devices, not through Stress servers. You can revoke Health access anytime in the Health app.

Stress is an iOS 26+ app for iPhone and iPad, with a companion watchOS 26+ Apple Watch app, plus Home Screen, Lock Screen, and watch face widgets. There is no Mac version: HealthKit is not available there.

You get the most from an Apple Watch that records HRV. An iPhone-only install can still show Health data other apps wrote, but Watch sampling is what makes a personal baseline useful. Keep Stress installed on both iPhone and Watch, and allow Health access, so samples and baseline parameters can stay in sync.

No. The 0–100 stress index and the four status labels—Fully Charged, Doing Fine, A Bit Tired, Feeling Rough—are a personal read of physiological load versus *your* recent baseline. They are not a diagnosis, treatment, or screening for disease, and they are not a psychological stress or mood score.

Use them as a calmer way to notice whether today looks usual, more drained, or more recovered. If you have health concerns, talk to a clinician. Stress does not replace medical advice.

Stress does not score psychological stress, anxiety, or mood. It estimates physiological load: how hard your autonomic nervous system appears to be working right now, mainly from Apple Watch HRV (and heart rate in Real-time mode) compared with your personal baseline.

A tense meeting can raise load, and so can poor sleep, illness, alcohol, or a hard training block. The number answers “is my body carrying more than usual for me?”—not “am I mentally stressed?” Mood logging is a separate HealthKit State of Mind record. It does not feed the stress index.

HRV is the tiny variation in time between heartbeats, stored in Apple Health as SDNN in ms. It is a widely used marker of autonomic balance: higher HRV often means you are adapting and recovering more easily; lower HRV often means more load. It is personal—your useful range is not someone else’s.

Stress does not treat a single HRV sample as a verdict. It reads HealthKit samples from Apple Watch, compares them with a comfort zone built from about the last 30 days at a similar time of day, then maps that into a 0–100 index. Day-to-day noise is normal. Trends against *your* baseline matter more than chasing a “good” number from the internet.

Real-time mode still ranks mainly from HRV. At rest, a new reading can land about every 6 minutes. Stress compares that HRV with your personal comfort zone for the matching time of day: inside the zone is usually everyday fluctuation; clearly below suggests more drain; clearly above suggests better recovery.

Recent heart rate can nudge the result with a limited weight so a reading feels a bit more tense or relaxed. A briefly faster pulse will not, by itself, jump you from okay to Feeling Rough. If heart rate is too old next to that HRV sample, it is ignored and scoring falls back to HRV only. Walking and workouts are not scored as stress.

Feeling Rough is the top status band, mapped from scores of 80 and above (with a small hysteresis buffer in Real-time mode so the label does not flicker). Stress may also surface a reminder when HRV is clearly below your usual comfort zone, near your personal low—not after one noisy sample.

That is a cue to slow down, not an alarm that something is medically wrong. The four labels are Fully Charged (0–34), Doing Fine (35–54), A Bit Tired (55–79), and Feeling Rough (80+). Older docs sometimes said “Struggling”; the app now uses Feeling Rough.

Stress does not score mood. It asks whether your body’s load has left *your* usual comfort zone. It builds a personal model from about 30 days of HRV (and resting heart rate), then compares a new sample with the zone for that time of day so nighttime recovery and daytime activity are not mixed into one number.

The status label comes from that zone first. The 0–100 score is a continuous scale for trends. Sleep, workouts, and movement help pause or contextualize scoring; they do not turn Stress into a mood questionnaire.

With little history, Stress stays conservative. Baseline reliability is graded by how many days you have built: under 7 days, 7–27 days, and 28 days or more. Clearer zone boundaries come as the model matures. One-off highs or lows do not easily redefine what is normal for you.

The algorithm also prefers where you *usually* sit over a single outlier. A higher heart rate from stairs usually will not flip you to Feeling Rough if HRV is still inside your zone. Trust grows with regular Watch wear, not with one perfect morning.

Status is the four-band label; the score is the 0–100 number used for charts. In Real-time mode, status uses a 2-point hysteresis buffer so you do not flicker across a boundary. HRV-only mode maps the score to a label directly so the badge matches the trend chart.

Bands are Fully Charged (0–34), Doing Fine (35–54), A Bit Tired (55–79), and Feeling Rough (80+). Neither the score nor the label is a medical diagnosis. They only help you see whether this reading looks usual, more drained, or more recovered for you.

The card’s comfort zone is the HRV band where you tend to be more stable at that time of day, built from about the last 30 days. It is not a medical cutoff and not a risk-alert line. Once the baseline is mature, values inside the zone are judged more conservatively as everyday status; only values clearly below or above can move into the extreme ends.

Leaving the zone is not a medical abnormality. It means you are clearly away from *your* usual range. Reminders, when they appear, still require more than a brief blip.

Usually not. Stress checks whether HRV has also clearly left your comfort zone. If HRV stays steady, a high heart rate is more likely walking, stairs, or exercise. Heart-rate influence is reduced in those cases.

Real-time scoring also pauses during recorded workouts and frequent walking, because pulse is unstable then. Exercise still belongs in Apple Health; it just should not rewrite your rest-time stress status.

Stress looks for several signals together, not a single noisy sample:

1. HRV is clearly below your usual comfort zone, even near your personal low.
2. Heart rate is also higher than usual, or load looks elevated, when heart rate is used.
3. The change is not just a very short everyday blip.

That mix cuts false alerts while still flagging days when your body seems taxed. A reminder is a suggestion to ease off. It is not a diagnosis.

Often, a higher HRV versus *your* baseline means easier recovery. It is not a contest with other people, and a single high reading is not automatically “healthier.” Stress reads HRV against about 30 days of your own data. A sudden jump far above your usual range can also be an unusual response—overreaching, illness, or measurement noise.

The healthier pattern is steady improvement over weeks, not chasing a peak. If HRV is often below your comfort zone, look at sleep, training load, alcohol, and illness before assuming the number is wrong.

Stress cannot prescribe training, but these habits often support HRV in published research and in everyday use of the app:

1. Regular exercise with enough recovery; avoid stacking hard days with poor sleep.
2. Enough sleep, often 7–9 hours, on a consistent schedule.
3. Sustainable work hours so your body has time to repair.
4. Balanced meals; very late, heavy dinners and high sugar/salt loads are common drags.
5. Go easy on alcohol; caffeine later in the day can also disturb sleep.
6. Stay hydrated; Stress can log water to Apple Health if you allow write access.
7. Slow breathing in the app (Relaxing Breath is free; other modes are Pro).
8. Time outdoors when you can.
9. Watch your own trend in Stress instead of copying someone else’s number.

None of this is medical advice. If HRV drops and you feel unwell, check in with a clinician.

These papers are background reading on HRV in exercise, sleep, and daily habits. They are not Stress-commissioned studies, and they do not turn the app into a medical device:

• Sandercock et al. (2005): review of exercise effects on HRV.
• Javaloyes et al. (2020): HRV-guided training prescriptions.
• Spiegelhalder et al. (2011): insomnia and HRV statistics.
• Young & Benton (2018): nutrition and physical/mental-health biomarkers.

Stress still computes on-device from *your* HealthKit samples and personal baseline. Citations explain why HRV is a useful signal; they are not a diagnosis protocol.

Your personal baseline is a physiological model built on-device from recent Apple Health HRV and RHR. It tracks your typical level, a time-of-day comfort zone, and less common personal highs and lows. Stress then compares a new sample with *your* zone instead of a population average.

The main statistics window is about 30 days. Evaluation uses a saved baseline from a strict earlier day so today’s still-syncing HealthKit samples do not make status flicker. That is why a new Watch needs regular wear before the zone feels like “you.”

Stress first computes your comfort zone for the matching time of day from about the last 30 days of HRV, then may fine-tune with heart rate in Real-time mode. Once the baseline is mature, HRV inside the zone usually stays in everyday status; clearly below suggests more strain; clearly above suggests better recovery.

The 0–100 index is that comparison on a continuous scale. Sleep timing also has its own bedtime baseline on Sleep details (same 30-day idea, at least 3 nights). Workouts pause real-time scoring rather than inflating stress.

Stress will not pretend a baseline is solid on day one. Reliability is graded by days of usable history: under 7 days (cold start), 7–27 days, and 28 days or more. Maturity in the UI is related but not identical: cold start under 7 days, learning through about two weeks, then mature when sample counts are high enough.

Early on, Stress still shows a cautious estimate. Wear the Watch through days and nights so HRV samples accumulate. After roughly two weeks the comfort zone usually settles; at about 28 days it is much more trustworthy for status.

Stress compares the current value with your comfort zone for that time of day:

1. In range: inside the zone—your more stable everyday state.
2. Below baseline: below the zone. For HRV, that often means more fatigue or load.
3. Above baseline: above the zone. For HRV, that often means easier recovery.

Once mature, the zone follows your usual swings; it is not one fixed width for everyone. Resting heart rate is read the other way around in places: a higher RHR versus your zone can mean more strain. Always read the metric’s direction on the card, not a single color rule.

The comfort zone is a stable HRV band from your usual swings over about the last 30 days at the matching time of day. It is not a medical diagnosis line and not a risk-alert line. It only answers: is this sample close to *your* more stable everyday state?

Inside the zone, Stress is conservative. Far below or above, status can move toward A Bit Tired, Feeling Rough, or a stronger recovery reading. One sample outside the band is a clue, not an emergency.

It shows the HRV baseline center and zone the algorithm is using right now—not your latest measured HRV. Based on when samples occur, the all-day model shifts with circadian rhythm: sleep periods usually lean more toward recovery, daytime more toward activity.

The “all-day reference” underneath helps you see how far this dynamic zone has moved relative to your full-day average. If the two look different, that is expected. Night and afternoon should not share one identical band.

Not directly. Occasional high or low HRV values are common with optical sensors, so Stress does not rely on ordinary standard deviation alone. It also looks at the median, typical distribution, and a more robust spread. The model cares more about where you usually sit than treating one spike as everyday status.

Very new baselines are still cautious. Keep wearing the Watch; extra days dilute outliers better than deleting the app.

Yes. Stress rebuilds candidate baselines from the latest HealthKit samples (about a 30-day window). A candidate saved today is used to evaluate later days, so today’s still-arriving samples do not rewrite today’s status in a loop.

As fitness, sleep, or seasons change, the zone drifts with you. A long HRV slump is not immediately treated as the new normal: the app can also show a separate long-term drift hint on Home without quietly changing the score. Open Stress regularly so backfill can catch up if you were away for several days.

Sleep details uses when you usually fall asleep over about the last 30 days—the same window idea as your personal baseline. You need at least 3 nights of evening sleep before the card appears. Naps that start roughly between 6:00 and 18:00 are not counted.

The Home sleep card, Sleep details, and sleep score all share this bedtime baseline. It is a clock-time habit, not a medical sleep-stage diagnosis. Stress reads Sleep Analysis from Apple Health; it does not run its own sleep lab on the Watch.

No. Bedtime baseline is your usual clock time for falling asleep, from about 30 days of evening sleep. Week avg sleep is the duration for this 7-day week, averaging only days that have a record.

Sleep duration is scored against the daily sleep goal you set in Stress—not against a historical average. You can be “in bed at your usual time” and still miss the duration goal, or the reverse. Read both: timing habit versus hours slept.

Sleep details hides that card if you have fewer than 3 usable evening nights, or if a personal baseline has not been saved yet. That is common in the first days after install, or if Sleep is off in Health for Stress.

Wear the Watch to sleep, keep Sleep tracking on in watchOS, and allow Sleep Analysis for Stress. Once more nights are in Apple Health, the card shows up on its own. Daytime naps do not count toward those 3 nights.

Switch in Settings → Calculation Mode. Both modes still use HRV as the main signal—not two unrelated algorithms.

1. Real-time mode (recommended, Pro after the in-app trial): at rest, stress can refresh about every 6 minutes. It ranks mainly from HRV, then folds in recent heart rate with a limited weight. A briefly faster pulse will not jump you from okay to Feeling Rough by itself. Walking or workouts are not scored as stress.
2. HRV mode (always available): follows Apple Watch automatic HRV samples only (often every 2–5 hours). Heart rate can still be shown, but it is not used in the score.

Choose HRV mode for a steadier, lower-power read. Choose Real-time when you want a more in-the-moment rest-time picture. The in-app 24-hour full-feature experience is not an App Store subscription free trial.

To protect accuracy, Real-time mode does not produce a new stress point when:

• You are walking or moving frequently (unstable heart rate)
• A workout is being recorded in Apple Health
• The Watch is in Low Power Mode
• The Watch is locked or worn loosely
• You are in high-motion situations such as running or riding in a vehicle

HRV mode is unaffected by those pause rules because it only follows automatic HRV samples. After you rest again, Real-time resumes from the next usable HRV plus heart-rate pair.

Apple limits how often third-party apps can start their own HRV sessions. Stress cannot raise Watch sampling on its own. The practical system option is turning on AFib History in Apple Watch Heart settings, which can increase automatic HRV to about every 15 minutes. That uses more battery, and it is an Apple health feature—not a Stress setting.

You can also take a manual 3-minute Breathe session in Apple’s Mindfulness app when you want an extra sample. Real-time mode uses heart rate more often; it does not create extra HRV samples by itself.

Stress reads extra HRV samples that Apple’s Mindfulness app writes to HealthKit. It does not run a separate camera or ECG:

1. On Apple Watch, open Mindfulness → Breathe.
2. Set the duration to 3 minutes or more.
3. Stay still, then when finished, lock and unlock your iPhone once so Health can sync.
4. After about a minute, open Stress; the new sample should appear and update baseline/stress.

If nothing arrives, check Health access for Heart Rate Variability and that the Watch was worn snugly.

A 3-minute Breathe session within 10 minutes of waking, before food or hard exercise, best reflects that day’s starting point. Sit or stand quietly; talking and walking add noise.

You can measure later too—the sample still lands in Apple Health—but it will reflect that later context, not morning readiness. Do not stack many sessions in a few minutes; watchOS may throttle how often HRV is stored.

Common causes:

• Too much movement, a loose Watch, or talking through the session
• Low Power Mode, Sleep Focus, or Theater Mode on the Watch
• Health access off for HRV, or Stress not allowed to read it
• Sessions too close together so watchOS limited new samples
• iPhone still locked, so HealthKit has not synced yet

Wear the Watch snugly, finish at least 3 minutes, unlock the iPhone, wait about a minute, then reopen Stress. Opening Apple Health and confirming a new HRV sample is the fastest way to see whether the Watch wrote anything.

Slow, paced breathing—especially a longer exhale—can shift autonomic balance toward the parasympathetic side: pulse often eases, and HRV can rise for a while. That is a physiological change, not a promise that anxiety “goes away.”

Stress’s breathing sessions can be written to Apple Health as mindfulness minutes when you allow write access. They do not by themselves rewrite your personal baseline. Think of them as a short downshift you can take when status looks heavy, not as treatment.

Four on-device patterns; follow the animation and haptics:

1. Relaxing Breath (4-4): even inhale/exhale for everyday settling. This mode stays available without Pro.
2. Deep Breathing (4-7-8): longer hold and exhale; often used when winding down for sleep.
3. Box Breathing (4-4-4-4): equal sides; a focus pattern.
4. Snore Relief (5-6): slightly longer cadence to practice steadier breathing.

Deep, Box, and Snore Relief are Pro features after the in-app trial. None of them diagnose sleep disorders. If a pattern feels too long, shorten it rather than forcing breath holds.

Follow the in-app visual and haptic guide when you can. If you feel short of breath or dizzy, shorten the phases and ease back toward the pattern. Consistency across days matters more than a perfect single session.

Stop if you feel unwell. Breathing exercises are optional recovery tools, not medical therapy, and they are not required for the stress index to work.

Stress ships four App Intents you can run from Siri, the Shortcuts app, Control Center, or automations:

1. Start Breathing
2. Log a Glass of Water
3. Check Current Stress
4. Log Mood

They talk to the same on-device data as the app. Water and mood write to Apple Health when permission is on. Check Current Stress reads the latest calculated status; it does not invent a new Watch sample by itself.

Siri phrases vary by language. In English, try:

1. “Start breathing with Stress”
2. “Begin a breathing exercise in Stress”
3. “Log a glass of water with Stress”
4. “Add water in Stress”
5. “Check my stress with Stress”
6. “Ask Stress if I’m stressed right now”
7. “Log my mood with Stress”
8. “Record my mood in Stress”

If Siri misses the app name, open Stress once, then add the actions in the Shortcuts app. Spoken language follows the system language, not only the in-app language picker.

On iPhone, open Shortcuts → tap + → search Stress → add an action. You can pin it to the Home Screen, run it from the Watch, or attach it to an automation (for example, start Relaxing Breath at bedtime, log water after lunch, or check stress in the morning).

For Start Breathing you can pick a mode; unset uses the default. Water amount can be 250 ml or 500 ml. Keep Health write access on for water, mood, and mindfulness if those actions should land in Apple Health.

Yes. In Shortcuts, Start Breathing can target Relaxing Breath, Deep Breathing, Box Breathing, or Snore Relief. If you leave the parameter unset, Stress prepares a session with the default option (Relaxing Breath).

Deep, Box, and Snore Relief still follow Pro gating after the in-app trial: the shortcut may open the paywall instead of starting those modes. Relaxing Breath remains available.

The shortcut records 250 ml by default. In Shortcuts you can choose 250 ml or 500 ml. The in-app plus button uses your saved usual glass size (customizable in Stress). All of these writes go to Apple Health dietary water, so Stress needs write permission first.

Logged water is health data in Apple Health, not a Stress cloud diary. Totals on Home and the Watch match whatever HealthKit already stored for that day.

Typical causes: Siri did not match the app name; Stress actions were never added in Shortcuts; Health read/write is off; or the device cannot write water right now. Also check that Stress is installed and has been opened once on that iPhone.

Open Stress, then search for Stress in Shortcuts and run the action there (that is more reliable than the first Siri attempt). For water or mood failures, open Health → your profile → Privacy → Apps → Stress and turn write access on.

Apple Health lists every raw HRV sample. Stress still reads those same HealthKit records, then chooses what to show: the Home card uses today’s latest sample; the top of HRV details uses that day’s average so one spike does not rewrite the whole day.

Date handling also follows the day you picked in Stress, not a rolling 24-hour bag of samples. If Health shows a sample and Stress does not, unlock the iPhone, pull to refresh, and confirm Stress is allowed to read Heart Rate Variability.

Both numbers are right; they answer different questions.

• Home card: your latest reading today, with the time underneath. It answers “where am I right now.”
• Top of the details page: the average for that day, so a single unusual reading does not skew the whole day.

Scroll down in details to see every raw reading. When you look back at a past day, both places show that day’s average, so they match.

Same idea as HRV: both numbers are right.

• Home card: your latest reading today, with the time on the card—“what is my pulse doing right now.”
• Top of the details page: the day average (the small “Day avg” label). A short spike from stairs or a workout will not rewrite the whole day.

On a past day, both places show that day’s average. Real-time stress may ignore heart rate that is too old next to an HRV sample; the card can still show the latest pulse for context.

watchOS gives every third-party complication a limited refresh budget per hour. Stress cannot update the face every few seconds. The complication shows cached stress/HRV/other metrics from the Watch app.

Open Stress on the Watch once, keep Background App Refresh on, and avoid Low Power Mode. After a new Health sample, unlock the iPhone so HealthKit can sync. Adding the complication from the Watch itself is more reliable than only using the iPhone Watch app.

“--” means Stress has nothing usable to show for that metric. The usual causes are: Health access off; no sample in the recent window (about 2 hours for some live cards); the Watch was off the wrist; or you are looking at a past day with no data.

Allow the types you care about in Health → Stress. Rest for a few minutes or run a 3-minute Mindfulness Breathe for HRV. Write types (water, mindfulness, State of Mind) need write access or logs will not stick.

Apple does not let apps see whether read access is on. Stress can only check whether it could read a sample from about the last 30 days. A warning therefore means “nothing readable lately,” not always “you denied access.”

Workouts stay empty if you have not logged a workout in 30 days. Workout Route exists only for outdoor GPS workouts; indoor, strength, and manual entries usually have no route. To review access: Health → profile → Privacy → Apps and Services → Stress.

In the app, open Settings → Feedback, pick a suggestion or issue, and send it. You can attach device info and logs. You can also reach us on Xiaohongshu, or email tonyhe1028@gmail.com.

We are a small team, so replies can take a few days. Feedback stays a support channel; it is not a cloud health account. Do not send medical emergencies there—use local emergency services.

watchOS often delays third-party notifications; a short lag is normal. If alerts never arrive: install Stress on both iPhone and Watch and confirm Home shows data; allow notifications in iOS Settings → Stress; turn Stress alerts on in the app; enable Background App Refresh for Stress on iPhone and Watch; leave Focus, Low Power, and Theater modes that silence the Watch.

Notifications follow on-device status. They are not a medical alarm. After a Watch reboot or reinstall, open Stress on the Watch once so it can receive baseline parameters over WatchConnectivity.

Install the Stress Watch app first, and use watchOS 26+. Add the complication on the Watch (press the face → Edit). The iPhone Watch app sometimes shows a stale preview; if the face looks wrong, remove it and add it again from the Watch.

Stress complications include stress, HRV, heart rate, steps, water, and active energy. They use cached values from the Watch app, not a live HealthKit query every second. Keep the Watch app installed even if you mainly glance at the face.

watchOS gives every third-party complication a limited number of updates per hour. Stress cannot refresh the face every minute. The complication shows cached stress/HRV/other metrics from the Watch app.

Open Stress on the Watch once, keep Background App Refresh on, and avoid Low Power Mode. After a new Health sample, unlock the iPhone so HealthKit can sync. That is the same budget limit described in the in-app FAQ—not a broken face.

Open Stress on Apple Watch → Settings (or the face-options entry) and pick a theme. Themes apply to Stress complications that support them, so the face matches the Watch app chrome.

Theme is an app preference. If iCloud settings sync is on, it can follow your iPhone language/layout preferences, but it does not sync health samples. After changing theme, glance at the face once; watchOS may wait for the next budgeted refresh.

The Watch needs baseline statistics from the iPhone (not raw HRV samples). Common causes: a brand-new Watch without enough history, Watch and iPhone disconnected, Health access off, Focus/Low Power modes, or Background App Refresh off.

Wear the Watch, open Stress on iPhone until Home shows a baseline, then open Stress on the Watch. Sync uses WatchConnectivity on your devices and does not go through Stress servers. A cold-start baseline under 7 days stays conservative on both devices.

The Watch can show cached values while the iPhone still lacks HealthKit read access or a recent sync. On iPhone: Settings → Privacy & Security → Health → Stress, and allow the categories you use (especially HRV and heart rate).

Unlock the iPhone, open Stress, and wait a moment. If it still fails, delete the iPhone app, restart the phone, and reinstall—Watch data in Apple Health is not deleted by removing Stress. Re-grant Health access after reinstall.

With few samples, Stress builds a cautious early baseline (under 7 days is a cold start). Status can look harsh or jumpy until the comfort zone has enough days. Wear the Watch through days and nights for about two weeks; judgments usually settle as you approach 28 days of history.

This is not a medical red flag and not proof that the algorithm is “too sensitive.” Real-time mode also pauses during walks and workouts, so rest-time samples matter more than a single busy afternoon.

Yes if you want the Watch face, notifications, and iPhone Home card to stay reasonably current. Stress’s background work is light: it reads HealthKit samples Apple Watch already collected and refreshes local caches. It does not stream health data to a Stress server.

Turn it on for Stress on both iPhone and Watch. Low Power Mode and some Focus settings still override it. Opening the app remains the most reliable way to force a sync.

Usually no. Stress relies on HealthKit samples the Watch already collects for Apple Health. HRV mode follows automatic samples (often every 2–5 hours) and is the lighter option. Real-time mode uses heart rate more often at rest (about every 6 minutes) and costs a bit more.

Complications use the system refresh budget; they do not run a separate heart-rate session every second. Turning on Apple’s AFib History can raise HRV sampling to about every 15 minutes and will use more Watch battery—that is an Apple setting, not a Stress toggle.

Pro membership follows your Apple ID. Sign in with the same account, open Stress, and tap Restore Purchases. Weekly and yearly subscriptions are managed by StoreKit; Stress does not keep a separate membership account in the cloud.

Health samples stay in Apple Health (and Health’s own iCloud sync if you use it). Stress does not upload HRV or stress history to Stress servers. In-app settings can sync via iCloud Key-Value Store. The in-app 24-hour full-feature experience is device-anchored and is not an App Store subscription free trial—it may not move with you to a new phone.

Use the same Apple ID that bought Pro, with network access, then tap Restore Purchases in Stress. If you changed App Store country or region, sign back into the account that originally subscribed and redownload.

Restore checks StoreKit entitlements. It cannot recover an expired subscription, and it cannot restore the in-app 24-hour experience (that is not a StoreKit trial). If Restore still fails, restart the iPhone and try again, or contact Apple ID support for billing issues.

Subscriptions are cancelled in Apple’s system, not inside a Stress account page: App Store → your profile → Subscriptions → Stress → Cancel Subscription. On iPhone you can also open Settings → [your name] → Subscriptions.

Cancelling stops the next renewal. You keep Pro until the current period ends. Stress cannot cancel it for you, and we do not see your payment card. Lifetime purchase is not offered yet—ignore any unofficial listing that claims otherwise.

Refunds are reviewed by Apple, not by the Stress developer. Use reportaproblem.apple.com, or App Store → your purchase → Report a Problem. We cannot issue a refund from inside the app or by email.

Have your Apple ID and order date ready. Turning off Stress or deleting the app does not cancel a subscription; cancel in Subscriptions first if you do not want the next charge.