ARC Download

Circadian rhythm tracker for iPhone

You’re not lazy. You’re on the wrong clock.

ARC tells you why you feel the way you do right now, gives you the one thing worth doing about it, and shows you over the weeks whether it’s working.

Download on the App Store Find your coffee cutoff
  • No account
  • No location access
  • No wearable
  • No sleep score

The sky on this page follows the time where you are. ARC’s screen does the same, all day.

One day with ARC

It explains today, and proves it over weeks.

Every screen below is the real app, on one Bear’s day: up at 7:00, in bed at 11:00, one coffee at 8:30.

Early morning

Why you’re tired, right now

What your body is doing right now, and the one thing that helps.

Every part of your day gets one sentence about what your body is doing, and one thing worth doing about it. Here that’s daylight: twenty minutes in the morning sets when your energy rises and falls for the rest of the day.

Peak

Last safe coffee, to the minute

From your bedtime, how fast you clear caffeine and what you’ve already had.

ARC works out the latest coffee you can have so that less than 50 mg is still in you at bedtime. Log a cup and the time moves.

Try it with your bedtime

Energy dip

Learns when you really crash

After about ten days it stops trusting your guess and uses what it measured.

Tap once when you crash. After about ten days ARC plans around the time it measured: a walk half an hour before, and daylight instead of another coffee.

Evening

See if it’s actually working

Crashes, week by week — and five-day experiments that show what helped.

Trends counts your crashes week by week and runs five-day experiments, like a walk before your dip. When something makes no difference, it says so.

Wind-down

Your day, on your home screen

Widgets that follow your phase through the day, without opening the app.

Widgets follow your phase on the home screen, so the next thing to do and the end of your coffee window are there without opening the app.

Try it now

When is your last safe coffee?

The same maths ARC runs, before you’ve logged anything. In the app it moves with every cup you log.

How does caffeine treat you?
Last safe coffee
5:54PM

A drip coffee (95 mg) then leaves 50 mg or less in you at bedtime, 11:00 PM.

This assumes nothing drunk yet today. ARC keeps it live as you log →

Your chronotype

Lion, Bear, Wolf or Dolphin?

Find your chronotype in two minutes. Your whole day is planned around it.

Lion

Usually up by 6:00 AM

Peak hours
7 AM–11 AM
Of people
15%

Early and sharp. Your best hours are gone by lunch — most people waste them in meetings.

The Lion schedule

Bear

Usually up between 6:00 AM and 8:30 AM

Peak hours
9 AM–1 PM
Of people
55%

You run with the sun. The most common type, and the one most damaged by late nights.

The Bear schedule

Wolf

Usually up after 8:30 AM

Peak hours
5 PM–10 PM
Of people
20%

You come alive when everyone else is winding down. The 9am world was not built for you.

The Wolf schedule

Dolphin

Sleeps lightly, whatever time they wake

Peak hours
10 AM–2 PM
Of people
10%

Light sleeper, quick mind. You need structure more than most — and it works faster on you.

The Dolphin schedule

How it works

Set it up once, then live your day.

  1. Answer a few questions

    Wake time, bedtime, when your energy crashes and how you take your coffee. ARC shows your chronotype and your first day before you choose a plan. No account.

  2. Do one thing at a time

    Each part of the day gets one sentence about what your body is doing and one thing worth doing, in the app and on your home screen.

  3. Tap when you crash

    One tap. After about ten days ARC plans around the dip it measured, and Trends shows whether your crashes are falling.

Pricing

Start with a free week.

Setup is free. You see your chronotype and your first day before you choose.

Annual

Save 81%

$49.99/ year

7 days free, then $49.99 a year. About $0.96 a week.

Weekly

$4.99/ week

Cancel anytime.

US prices. The App Store shows yours. Payment is charged to your Apple ID. Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period, and you can manage or cancel them in your App Store account settings.

A student, or the price is a real barrier? Write to pritamfinds@gmail.com and we’ll work something out.

Questions

Before you download.

Do I need a wearable?

No. ARC works from what you tell it in setup and a few taps a day. There’s nothing to wear or connect.

Does ARC need my location?

No. It estimates sunrise from your time zone, so it never asks for location access.

Where is my data kept?

Your log is stored on your iPhone. There’s no account to create and nothing to sign in to.

How is the coffee cutoff worked out?

From your bedtime, how fast you clear caffeine and every drink you log, so that less than 50 mg is still in you when you go to bed. It moves each time you log a cup.

Why no sleep score or streaks?

On purpose. ARC tells you what your body is doing and what helps. It doesn’t grade your day.

Does it work for shift workers?

Yes, if your schedule is steady: set your own wake time and bedtime and the whole day follows. Rotas that change every few days are much harder to plan around.

Which languages?

English and German.

How do I cancel?

In iPhone Settings, tap your name, then Subscriptions, then ARC. Cancel at least 24 hours before the period ends and you won’t be charged again.

Is ARC medical advice?

No. ARC is a wellness app, not a treatment. If tiredness is affecting your health, talk to a doctor.

Stop fighting your clock.

Find your chronotype, and get a day built around it.

Download on the App Store

Free setup. 7 days free on the annual plan.