Cafactor vs Sthenos

Caffeine Hourglass is now Cafactor — rebuilt from the ground up. What began as a simple caffeine timer has evolved into a full physiological model that adapts to your biology in real time. Version 2.0 isn't an update. It's a new category of health tool. Know your caffeine. Protect your sleep. Log a drink in seconds. Cafactor computes your real-time caffeine curve using a peer-reviewed pharmacokinetic model — complete with a realistic absorption phase, first-order decay, and your personal biological parameters. See whether you can safely have one more coffee, and exactly when your levels will drop below your personal sleep threshold. Personalised to your body Set your sex, height, weight, and age. Cafactor applies the Boer (1984) lean-body-mass formula to calculate how caffeine distributes in your specific body. Add smoking status, hormonal medication, or pregnancy for a half-life that's truly yours. Your tolerance to caffeine — derived automatically from 7-day history — rounds out the picture. HealthKit: exponentially smarter Connect Apple Health and Cafactor transforms from a tracker into an adaptive metabolic coach: • Exercise modifier — Recent vigorous workouts temporarily speed up your metabolism. Cafactor detects this from HealthKit and adjusts your decay curve automatically. • Sleep-adaptive threshold — Last night's poor sleep tightens your safe window today. Great sleep? More room for your morning ritual. • HRV & Recovery (Apple Watch) — Daily heart-rate variability fuses with sleep quality to create a PhysiologicalState score, shifting your optimal intake windows and adjusting thresholds by up to 40%. • Progressive calibration — Recency-weighted regression over 30 days of sleep and HRV feedback automatically refines your personal half-life, growing from Preliminary to Reliable confidence as data accumulates. Pro features Unlimited history · Trend, sleep quality and scatter charts · Last safe caffeine time · Four smart notifications (morning window, safe window, withdrawal, recovery) · Shareable weekly report · Siri shortcuts · Unlimited custom drinks Free, forever, offline Core tracking is always free. No account. No internet. No data leaves your device — ever.

Do you know how much energy you actually have left right now? Sthenos turns your Apple Watch into a live energy score — a single number from 0 to 100 that reflects how recharged or depleted your body is, and whether you're charging or draining at this moment. No guesswork. No manual logging. Just honest, science-backed insight from the sensors you already wear. HOW IT WORKS Sthenos isn't a daily snapshot or a one-off rating. It's a running energy level, updated through the day: • You recharge during genuine rest and sleep — when your heart rate settles and your HRV rises relative to your own baseline. • You drain from activity, elevated heart rate, and physiological stress. • Recent training still counts — a hard workout keeps weighing on you for days, so you can tell when you're truly recovered. Everything is judged against YOUR personal baseline, not population averages. Sthenos learns your normal (about two weeks — faster if you've already been wearing your watch) and calibrates the score to your body. WHAT YOU GET • The heart gauge — your score fills a heart that empties as you deplete and refills as you recover. The number sits inside it and inverts where the waterline crosses, and it beats at your own resting heart rate. • Energy flow — a live read on whether you're charging or draining this hour, and why. • Sleep, Recovery, Heart and Freshness — the four things moving your score, each one tappable for a plain-English explanation of what it means today. • Trends — your history drawn as a tide, at a day, a month, three months or six, from the same model as the live score. • Training load — Fitness, Fatigue and Form from the training impulse of every workout, with the raw daily load drawn underneath, plus the acute:chronic ratio and its sweet spot. • Vitals — every reading your watch takes, each on a rail showing your own normal range and where today sits: heart rate, resting HR, HRV, blood oxygen, respiratory rate, VO₂ max, steps, active energy, sleep, wrist temperature, weight. • On-device AI insights — a short, plain-language read on your day, generated on your iPhone with Apple Intelligence. • Apple Watch app and complications — your score, factors, vitals and training load on the wrist, plus the score as a filling heart, a training-load complication, and a configurable single metric. • Home-screen widgets — a score widget, plus two configurable Vitals widgets where you choose every metric shown. • The science, in-app — an About tab explaining how the score is calculated, with links to the research, and saying plainly where the evidence is contested. PRIVATE BY DESIGN Your health data never leaves your device. Sthenos reads from Apple Health and computes everything locally — no account, no sign-up, no tracking, no ads, no servers. Even the AI insights run on-device. WHAT IT READS (read-only, from Apple Health) • For the score: HRV, resting heart rate, heart rate, sleep, workouts • For Vitals: blood oxygen, respiratory rate, VO₂ max, steps, active energy, wrist temperature, body mass • For the optional fitness-age card: date of birth, biological sex, height, body composition, exercise and stand time, walking heart rate, mobility measures, daylight, blood glucose and pressure Nothing is written back to Apple Health. REQUIRES • iPhone with iOS 18 or later • Apple Watch (Series 4 or later) worn regularly, including overnight, for HRV and sleep. The watch app needs watchOS 11. • On-device AI insights require iOS 26 and an Apple-Intelligence-capable iPhone Sthenos is a personal wellness tool. It is not a medical device and does not provide medical advice. Apple Watch HRV is suitable for personal trends and is not clinical-grade. Always consult a healthcare professional for medical concerns.