Your Whoop can tell you your nervous system is stressed. It can't tell you your reaction time is 80ms slower than yesterday. BASLN measures your brain directly with six research-validated cognitive tests. Five minutes. Every morning.
Free for first 10 sessions · All data stays on your device
HRV, sleep stages, and respiratory rate tell you about your autonomic state. They don't tell you how fast you react, how much you remember, or how well you focus. Those require cognitive tests.
Each test is a compressed version of an instrument used in peer-reviewed cognitive research. Together they cover the core dimensions of operational cognitive performance.
Reaction time · Vigilance
Tap the moment a counter appears. No learning effect. The gold-standard measure of fatigue in sleep deprivation research.
Run on the ISS as the astronaut Reaction Self-Test. Used in thousands of peer-reviewed sleep studies.
Working memory
Watch a shape appear in one of 9 positions. Report when the current position matches the one two steps ago.
Adapted from the NASA Cognition battery used in astronaut operational performance research.
Processing speed
Match digits to symbols as fast as possible against a reference key. The single best predictor of complex operational performance.
Explained 34% of the variance in simulated spacecraft docking performance (Hartley).
Executive function · Inhibitory control
Identify the color a word is printed in, not the word itself. Measures your ability to override automatic responses.
One of the most validated executive-function instruments in experimental psychology.
Processing speed under load
Verify whether simple equations are true or false, under time pressure. A compact proxy for cognitive throughput.
Adapted from Walter Reed and other operational cognitive test batteries.
Cognitive flexibility · Task switching
Connect alternating numbers and letters as fast as possible. Measures the cost of switching rules on the fly.
Core measure in clinical neuropsychology since Reitan (1958).
The same experimental loop used in operational fatigue research, compressed for daily use on your phone.
Take the battery once a morning for five sessions. BASLN learns your personal cognitive signature across the six dimensions.
Every subsequent session scores you 0–100 against your own norm. No population percentiles. Just you versus you.
Low score? The app surfaces evidence-ranked recovery protocols (caffeine timing, bright light, HIIT, nap) with time-to-effect estimates and citations.
Retest later in the day. See whether the intervention actually moved your numbers, or whether you were placebo-ing yourself.
Baseline for a week. Start an intervention. Test daily. Watch the number move, or don't. Either way, you have data.
iPhone · iOS 17+ · All data local