Reaction Time
How fast can you click?
Wait for the screen to turn green, then click as fast as you can. Measures your visual reaction time in milliseconds.
The Zehano reaction time test measures how quickly you respond to a visual cue. It is one of the cleanest indicators of how alert you are in the moment, and it varies with sleep, stress, and time of day. Take the test, watch the green flash, and click as fast as you can. Your five-round average is what to track.
How to use the Reaction Time Test
- Start the test. Click the test area to begin. Keep your finger ready over the mouse or the screen.
- Wait for green. The area turns red while waiting. Do not click. Random delay between one and five seconds.
- Click on green. The instant the colour changes, click. Your reaction time appears in milliseconds.
- Repeat for the round. Do five trials. Your average across the five is the real number to watch.
- Track your best. Your fastest result of the session saves automatically in your browser.
Benefits
- Diagnostic, not training. A quick read on how alert you are right now. Useful before driving or starting demanding work.
- Sleep barometer. Reaction time tracks sleep quality closely. A slow morning often reflects last night, not your skill.
- Stress sensitive. Anxiety and stress slow reaction times. Trend changes can flag rising background stress.
- Practical and free. No login, no ads, no signup. Runs in your browser, saves locally.
The science
The average adult reaction time to a simple visual cue is around 250 milliseconds, with most healthy adults landing between 200 and 280. The number reflects signal travel from retina to visual cortex to motor cortex to fingertip. Jain and colleagues' 2015 comparative study showed visual reactions are typically 30 to 50 milliseconds slower than auditory ones because of slightly longer neural pathways. The biggest acute influence is sleep: Lim and Dinges' 2010 meta-analysis found that even mild sleep restriction reliably slows simple reaction times.
Practice on a specific test improves your score on that test, but the gains rarely transfer to faster reflexes in real-life situations. Sleep, hydration, and short breaks help more than drilling.
Tips for best results
- Test at the same time each day for fair comparisons.
- Sit upright and keep your finger lightly poised, not pressed.
- Run five trials and use the average, not your single best.
- Skip the test right after meals or during the early-afternoon dip.