You're not lazy.
You're on the wrong clock.
ARC explains why you feel tired right now, gives you the one thing worth doing about it, and proves the answer over weeks by halving your afternoon crashes.
“You're in your light window. Twenty minutes outside now sets up your whole day.”
Light first, coffee later
Delay caffeine 90 minutes today
Tired in a way
sleep doesn't fix?
You've been told you're undisciplined because you can't function at 8:00 AM, or you're wired at midnight. It's not a character flaw — it's your chronotype. Your body runs on a biological clock, and most of us are fighting ours all day.
Mornings feel like fog until 10am
Your cortisol rise is delayed, keeping you in sleep mode long after your alarm.
The 3pm crash every single day
Drinking coffee at the wrong time blockades adenosine receptors, ensuring an afternoon crash.
Wide awake exactly when you need to sleep
Fluorescent lights and digital screens suppress melatonin, pushing your sleep gate back hours.
THE 4 CHRONOTYPES
There are four clocks.
Which is yours?
Your chronotype dictates when you're wired to wake, peak, and sleep. A 22-step onboarding across 6 acts pinpoints yours.
Lion
Early RiserEarly riser, peaks before noon, fades by evening.
Read full guide →Bear
Solar RhythmFollows the sun; 50% of the world runs on Bear time.
Read full guide →Wolf
Night OwlSlow mornings, sharp late — built for the night.
Read full guide →Dolphin
Light SleeperLight, sensitive sleeper with a busy mind.
Read full guide →
Tactical features.
Biological precision.
The day's plan & one ask
One sentence, then a plan for the day. Exactly one prioritized ask at a time—get light, start your hard task, or take a walk—drawn as the first item of your plan. No cluttered dashboard, no decision fatigue at 7am.
“You're in your light window. Twenty minutes outside now sets up your whole day.”
Get 20 min of light
Runs in Dynamic Island · Phone stays in pocket
Dynamic caffeine cutoff
The last safe coffee time, computed dynamically from your bedtime, caffeine sensitivity, and every drink logged today. Three distinct states (ahead, passed, exhausted) ensure under 50mg of active caffeine remains at bedtime.
Solar morning light
Real astronomical sunrise calculated from your device's timezone with zero GPS permission. A 20-minute calibrated timer runs as a Live Activity in your Dynamic Island so your phone stays in your pocket, with indoor fallbacks for dark winter mornings.
Tuned to your real biology
Every day explained in your own numbers. 'This is adenosine, not laziness.' Mechanism, never verdict—no guilt trips, arbitrary 0-100 sleep scores, rings, or streaks. Just clear physiological facts.
“This is adenosine, not laziness. Your sleep debt is 42m; we shifted your focus window accordingly.”
Receipts over weeks
Watch your afternoon crashes drop from 3.5 to 1.0 a week—measured from your own check-ins, not asserted. Backed by 14-day adherence dot strips, 5-day habit experiment loops, and 7 automated biological event loops.
HOW IT WORKS
From confused to in-sync
in one evening.
Discover your profile
A 22-step onboarding across 6 acts reveals your chronotype, focus peaks, and natural circadian sleep pressure.
Follow your plan
One sentence, one action at a time. Follow a live dynamic day plan with Dynamic Island timers and dynamic caffeine cutoffs.
Get the measured receipts
Watch your afternoon crashes drop from 3.5 to 1.0 a week—proven from your own check-ins and verified by 5-day experiment loops.
Bear Chronotype
Solar-synchronized. 50% of humans. Cortisol peak at 8:30 AM.
“You're 40 minutes into your dip. Move 5 min to clear adenosine.”
THE SCIENCE
Built on chronobiology,
not hustle culture.
Your energy isn't random — it follows a circadian rhythm set by light, sleep, and timing. ARC turns decades of sleep and circadian science into simple, personalized actions.
- Sleep Pressure
Adenosine
The Adenosine Clear
Adenosine builds up in your brain from the moment you wake. It creates sleep pressure that makes you feel tired. Caffeine doesn't remove it — it just masks the signal. ARC calculates the exact window to wait before your first coffee, preventing your 2 PM crash.
- Morning Anchor
Cortisol
Cortisol Pulse Timing
Morning sunlight triggers a cortisol spike that sets your entire daily rhythm — including when you'll feel alert and when melatonin will rise 12–16 hours later. ARC gives you a precise sunlight window within minutes of your wake time.
- Sleep Onset
Melatonin
Digital Sunset Protocol
Melatonin release is triggered by your morning cortisol spike and suppressed by evening light. ARC's Digital Sunset protocol tells you exactly when to dim screens and lights to let your natural sleep signal rise — every night.
Sample Biological Directive
“You're 40 minutes into your afternoon dip. This is adenosine, not laziness.”
Mechanism, never verdict. ARC explains today in one sentence using your own numbers, with the physiological reason one tap away under “Why this works”.
Research Foundation
Dr. Andrew Huberman
Stanford Neuroscience Lab
Light exposure, cortisol rhythms & adenosine management
Dr. Matthew Walker
UC Berkeley Center for Sleep Science
Sleep architecture, circadian cycles & melatonin optimization
Trusted by sleep seekers
& peak performers.
“Nice to know how my body works — the optimal time to drink coffee and when to cut it off so it doesn't affect my sleep.”
“As a night-shift software engineer, ARC is the only circadian app that actually supports inverting guidelines safely. Absolute game changer.”
“The caffeine decay tracker is scarily accurate. My sleep quality score shot up 40% after shifting my cutoff window.”
Sound Familiar?
Built for people who are
done guessing.
High-Performers
Founders, engineers, and creators who need maximum focus hours. ARC maps your peak windows so you stop guessing.
View Guide →Coffee Drinkers
You drink coffee every day but have never understood how it actually interacts with your sleep. ARC shows you the exact cutoff minute.
View Guide →ADHD Professionals
Structured visual missions replace overwhelming to-do lists. Biology-aligned triggers your brain actually responds to.
View Guide →Sleep Seekers
Sleeping 7-8 hours but still exhausted? It's a timing problem, not a duration problem. ARC fixes the root cause.
View Guide →Biohackers
Real data and correlations — not just streaks and checkboxes. Understand the cortisol-melatonin rhythm driving your entire day.
View Guide →Shift Workers
Design your flexible schedule around biology, not just calendar availability. Anchor your rhythm regardless of when you wake up.
View Guide →
PRICING
Start syncing
today.
Subscription auto-renews, cancel anytime. Managed through the App Store.
Weekly
$4.99/ weekGet Instant AccessCancel anytime in App Store
Annual
Best Value$39.99/ yearGet Instant Access~$0.77 / week • Includes full ARC 2.0 features
Have questions or a tight budget?
Whether you want to understand the science better, or you're a student experiencing financial hardship, we don't want price to be a barrier to your health.
Payment charged to Apple ID at purchase confirmation. Subscription auto-renews unless canceled 24h before end of period. Manage in App Store account settings.
FAQ
Questions
answered.
Why doesn't ARC have sleep scores (0-100), rings, or streaks?
A number out of 100 invites gaming an arbitrary score rather than understanding your body. Breaking a streak causes app abandonment. ARC rejects gamification and focuses on physiological mechanisms ('This is adenosine, not laziness') and measured proof—like halving your afternoon crashes.
How does the dynamic caffeine cutoff work?
Unlike generic 'no coffee 8 hours before bed' rules, ARC computes your cutoff dynamically from your target bedtime, personal metabolic sensitivity (fast, normal, or slow), and every drink logged today to ensure under 50mg of active circulating caffeine remains at bedtime.
Do I need a wearable or Apple Watch?
No. ARC works completely standalone from your wake time, light timers, and quick one-tap check-ins. It calculates your biological rhythm without requiring expensive hardware.
Does ARC require GPS location permissions for morning light?
No location permission is ever requested. ARC calculates the true astronomical sunrise and solar angles directly from your device's time zone.
What is the 5-day experiment loop?
ARC tests one habit change at a time (like an earlier cutoff or pre-dip walk) for five days against your recorded history, scoring the outcome with honest verdicts including 'no difference'.
Is my data private?
Yes. ARC is built on local-first SQLite on your iPhone. There are no accounts, no logins, and no remote cloud database holding your check-ins or habits.
Does it work for shift workers?
Yes. ARC features dedicated night-shift and flexible protocols that invert and calibrate guidance around your actual wake time.
How do I cancel?
Anytime in one tap through your Apple ID subscription settings.
START TODAY
Stop fighting
your clock.
Find your chronotype and build a day that works with your biology.
Download on theApp StoreFree to download · Cancel anytime · 100% On-Device Privacy