Withings has added more proactive health insights to the ScanWatch 2 through HealthSense 4, an operating-system and algorithm update announced at IFA Berlin on September 5, 2025. The update can identify changes in temperature and other signals linked to possible illness, menstrual-cycle timing, fatigue, sleep and respiratory patterns.
It is important to clarify what changed: this is primarily a software and algorithm expansion, not an entirely new ScanWatch 2 hardware generation. The watch still collects the underlying measurements; HealthSense 4 interprets them more proactively. Withings’ “predictive AI” should therefore be understood as personalized pattern analysis—not a system that diagnoses disease or predicts a specific medical event.
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What changed for ScanWatch 2 owners?
HealthSense 4 was announced for the ScanWatch 2, ScanWatch Nova and ScanWatch Nova Brilliant. Withings says the system analyzes 35 health parameters to find changes relative to a wearer’s usual patterns.
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- The watch collects signals such as heart rate, temperature, oxygen saturation, activity, sleep and HRV.
- Algorithms compare those measurements with the wearer’s personal baseline.
- The Withings app combines the data into trends, scores, notifications or suggestions.
That distinction matters. The update can provide earlier awareness of an unusual pattern, but it does not turn the ScanWatch 2 into a diagnostic device.
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- TIMELESS DESIGN – Hybrid smartwatch with analog hands and digital health tracking. Stainless steel case with sapphire glass for durability. Available in multiple sizes and finishes.
- 35 DAYS BATTERY LIFE– Built for the long run with up to 35 days of continuous use on a single charge. Provides uninterrupted daily and nightly health tracking with extended power.
- HEALTH MONITORING– 30s medical-grade ECG and continuous heart rate tracking with AFib detection via the Withings ECG App. Includes high and low heart rate notifications.
- SLEEP, WORKOUT & RECOVERY INSIGHTS – rack sleep stages, breathing, and over 40 sports with VO₂ max and heart rate zones. Get a Vitality Score and 1 month of Withings+ for personalized insights.
- COMPATIBILITY & PROPRIETARY OS – Seamlessly connects to Android and iOS via the Withings App. Powered by our HealthSense OS with on-device machine learning for precise health metrics.
What does the predictive health feature actually predict?
Possible illness signals
Withings says changes in body temperature and other measurements can generate alerts associated with possible early signs of illness. The watch does not identify a pathogen, confirm an infection or establish that a user has a fever.
Wrist-skin temperature can be affected by ambient conditions, exercise, alcohol, sleep environment, fit and whether the watch was worn consistently. If the watch suggests an unusual temperature change, check symptoms and use a validated thermometer when fever is a concern.
Menstrual-cycle predictions
The updated algorithms can use temperature trends and cycle history to help anticipate the possible beginning of a menstrual cycle. Accuracy can be reduced by irregular cycles, limited history, inconsistent overnight wear, hormonal-contraception changes, pregnancy, postpartum changes, perimenopause, illness or major stress.
This feature is not contraception, pregnancy confirmation or a clinical fertility tool.
The Vitality Indicator
The Vitality Indicator is a Withings+ feature that combines inputs including heart-rate variability, activity, body temperature, oxygen saturation, respiratory rhythm and sleep quality. Withings says it estimates energy levels and can suggest possible contributors to fatigue.
In practice, it is a composite wellness score—not a direct measurement of physiological energy. A low result could reflect poor sleep, an unusually hard workout, incomplete data, temperature changes or ordinary algorithmic variation. It should not be used alone to change medication, treatment or training plans.
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- TIMELESS DESIGN – Hybrid smartwatch with analog hands and digital health tracking. Stainless steel case with sapphire glass for durability. Available in multiple sizes and finishes.
- 35 DAYS BATTERY LIFE – Built for the long run with up to 35 days of continuous use on a single charge. Provides uninterrupted daily and nightly health tracking with extended power.
- HEALTH MONITORING – 30s medical-grade ECG and continuous heart rate tracking with AFib detection via the Withings ECG App. Includes high and low heart rate notifications.
- SLEEP, WORKOUT & RECOVERY INSIGHTS – rack sleep stages, breathing, and over 40 sports with VO₂ max and heart rate zones. Get a Vitality Score and 1 month of Withings+ for personalized insights.
- COMPATIBILTY & PROPRIETARY OS – Seamlessly connects to Android and iOS via the Withings App. Powered by our HealthSense OS with on-device machine learning for precise health metrics.
New sleep and respiratory information
HealthSense 4 adds or expands:
- REM-sleep tracking and more detailed sleep architecture.
- Nocturnal respiratory-rhythm tracking.
- Existing measures such as sleep duration, interruptions and overnight HRV.
Sleep stages are algorithmic estimates based on movement and physiological signals. Respiratory-rhythm trends may help reveal changes over time, but neither replaces polysomnography or establishes a sleep-disorder diagnosis.
One unusual REM or respiratory reading is rarely meaningful by itself. Look for persistent trends across several nights, especially when the watch has been worn consistently.
What the ScanWatch 2 measures
The hardware remains a hybrid analog-digital watch available in 38mm and 42mm sizes. Withings lists the following capabilities on its ScanWatch 2 product page:
- 24/7 heart-rate tracking.
- ECG recording.
- Blood-oxygen measurements.
- 24/7 temperature tracking.
- Overnight HRV.
- Sleep tracking, including REM.
- Respiratory-related metrics.
- Steps, activity, workouts, elevation and calories.
- High- and low-heart-rate notifications.
- Menstrual-cycle tracking and smartphone notifications.
Withings advertises up to 35 days of battery life. That is a manufacturer claim, not a guaranteed runtime; ECG use, continuous sensing, workouts, notifications and settings can reduce battery life.
Temperature tracking is designed to identify deviations from a personal baseline. It is not a medical thermometer, and wrist temperature is not equivalent to oral, ear or core temperature.
Which features require Withings+?
Withings says health data remains available in the free Withings app, while Withings+ adds interpretation, coaching and clinical services. The exact feature boundary can vary by market, app version and account.
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- TIMELESS DESIGN – Hybrid smartwatch with analog hands and digital health tracking. Stainless steel case with sapphire glass for durability. Available in multiple sizes and finishes.
- 35 DAYS BATTERY LIFE– Built for the long run with up to 35 days of continuous use on a single charge. Provides uninterrupted daily and nightly health tracking with extended powe.
- HEALTH MONITORING– 30s medical-grade ECG and continuous heart rate tracking with AFib detection via the Withings ECG App. Includes high and low heart rate notifications.
- SLEEP, WORKOUT & RECOVERY INSIGHTS – rack sleep stages, breathing, and over 40 sports with VO₂ max and heart rate zones. Get a Vitality Score and 1 month of Withings+ for personalized insights.
- COMPATIBILITY & PROPRIETARY OS – Seamlessly connects to Android and iOS via the Withings App. Powered by our HealthSense OS with on-device machine learning for precise health metrics.
In the United States, Withings’ current Withings+ page lists:
- Withings Intelligence and a 24/7 Health Assistant.
- Smart trends and insights.
- Daily Readiness and long-term Health Improvement scores.
- ECG-powered cardiologist reviews.
- A live nutritionist video session.
- Sleep Clinic Assessment where eligible.
The listed U.S. price is $9.95 per month or $99.50 per year. Withings’ U.S. store advertises a one-month free trial with device purchases, although eligibility and promotional terms can change. A buyer paying the listed ScanWatch 2 price of about $369.95 and retaining the annual subscription would spend approximately $469.45 in the first year before any discount or promotion.
Because some of the most interpretive features are subscription-based, prospective buyers should check the individual feature’s availability rather than assume that every HealthSense 4 insight is free.
How to get the update
- Update the Withings app.
- Make sure the ScanWatch 2 is paired and synchronized.
- Install any available watch firmware update.
- Wear the watch consistently, particularly overnight, so the app can establish a personal baseline.
- Check whether the insight you want appears in the free app or the Withings+ section.
Menu names can change between mobile operating systems and app releases, so owners should follow the current in-app update prompts rather than rely on an old fixed menu path.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is the predictive AI medically reliable?
The answer depends on the feature. Withings’ ECG functionality uses the Withings ECG App, but regulatory clearances, availability and clinical validation differ by country. The company’s ECG FAQ documents regional differences.
That regulatory context should not be extended to every HealthSense 4 feature. Predictive illness signals, Vitality scores, fatigue suggestions, sleep staging and cycle predictions should be treated as wellness guidance unless a specific regional claim says otherwise.
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- TIMELESS DESIGN – Hybrid smartwatch with analog hands and digital health tracking. Stainless steel case with sapphire glass for durability. Available in multiple sizes and finishes.
- 35 DAYS BATTERY LIFE– Built for the long run with up to 35 days of continuous use on a single charge. Provides uninterrupted daily and nightly health tracking with extended power.
- HEALTH MONITORING– 30s medical-grade ECG and continuous heart rate tracking with AFib detection via the Withings ECG App. Includes high and low heart rate notifications.
- SLEEP, WORKOUT & RECOVERY INSIGHTS – rack sleep stages, breathing, and over 40 sports with VO₂ max and heart rate zones. Get a Vitality Score and 1 month of Withings+ for personalized insights.
- COMPATIBILITY & PROPRIETARY OS – Seamlessly connects to Android and iOS via the Withings App. Powered by our HealthSense OS with on-device machine learning for precise health metrics.
The reviewed announcement materials do not establish how often the predictive illness alerts produce false positives or false negatives, nor do they provide independent validation for those claims. A wearable notification should prompt attention, not panic.
Withings also says ECG and irregular-heart-rhythm features are not intended for people with a pacemaker, implantable cardioverter-defibrillator or another implanted electronic device. Regional guidance should take priority.
What to do when the watch flags something unusual
- Possible illness: check your actual symptoms, review recent sleep, exercise, alcohol, travel and stress, and confirm suspected fever with a thermometer.
- Erratic temperature: check fit, overnight wear, charging gaps and bedroom temperature before interpreting the trend.
- Unexpected cycle prediction: treat it as an estimate, particularly when cycles are irregular or recent hormonal, postpartum or perimenopausal changes are involved.
- Low Vitality after exercise: consider normal recovery demand, poor sleep or incomplete data rather than treating the score as a diagnosis.
Seek medical advice for persistent or worsening symptoms. Emergency symptoms require urgent care regardless of what the watch reports—or fails to report.
Who should consider the ScanWatch 2?
The update makes the ScanWatch 2 more appealing to people who want discreet analog styling, long battery life and passive health trends. It is particularly logical for existing Withings users who already use the company’s scales, sleep products or cardiovascular devices, because those measurements can be viewed in the same ecosystem.
The watch is a weaker fit for athletes who need onboard GPS, maps, detailed workout screens or advanced training-load analysis. It is also unsuitable for anyone seeking a diagnostic device or an AI alert that can replace clinical evaluation.
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Bottom line
HealthSense 4 gives the existing ScanWatch 2 a more proactive role: it can compare temperature, sleep, respiratory, cardiovascular and activity patterns with a personal baseline and turn them into useful prompts. That is a meaningful software improvement for owners who want passive trend detection.
But “predictive AI” is best read as personalized algorithmic analysis, not early diagnosis. The ScanWatch 2 cannot confirm illness, measure clinical fever, diagnose sleep disorders or make medical decisions. The update is most valuable when used as a long-term wellness signal—and interpreted alongside symptoms, reliable measurements and professional medical advice.
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