ARC for Biohackers
A habit-experiment app for Biohackers
Test one habit for five days and get an honest verdict, even 'no difference'. ARC measures your afternoon dip from your own check-ins. No wearable needed.
Download on theApp StoreThe Problem
- ✕Basic habit trackers lack scientific depth
- ✕Wearables measure but don't tell you what to change
- ✕Generic health advice doesn't account for individual differences
- ✕Missing the connection between light, caffeine, and deep work
How ARC Helps
ARC treats your habits as experiments: change one thing for five days, compare with the two weeks before, and keep what actually moved your energy.
Key Features
- ✓Five-day single-habit experiments with honest verdicts
- ✓Trends: crashes per week, dip timing, what each habit changed
- ✓Schedule-drift detection
- ✓No account. Your log stays on your iPhone.
How the Experiments Work
ARC proposes one change (an earlier cutoff, morning light, a walk before the dip, rest at the dip, or a consistent wake time), runs it for five days, and scores it against the fortnight before using logs you've already made. "No difference" is a real verdict: it takes something off your list. Experiments are offered from day ten, once there's a baseline.
One change at a time is the point. Change five things at once and you learn nothing you can keep, which is also why generalised advice so often fails.
What Gets Measured
Energy check-ins (low, medium or high) are the outcome. From them, Trends shows afternoon crashes per week, when your dip lands (the median offset after waking), 14-day strips for morning light and cutoff held, and whether your wake time is drifting. At 28 days you get a then-vs-now report.
ARC doesn't read Apple Health, connect to wearables, or measure cortisol, melatonin or light levels. It runs on one-tap logs. For the light side of the science, see the morning sunlight guide.
See Today's Sunrise and Light Window
See today's sunrise and your morning light window, the lever most of ARC's experiments start from.
Questions from Biohackers
Why is there no sleep score?▼
Because a score is a verdict, and ARC tries to show mechanisms instead. Here's the full reasoning.
Do I need a wearable?▼
No. ARC works from one-tap check-ins and the drinks you log. It doesn't read Apple Health or connect to a watch or ring.
Where is my data stored?▼
Your log stays on your iPhone. No account. The one exception is the daily sentence: to write it, ARC sends a short timing summary (wake time, bedtime, dip time and today's caffeine) to a language model.