TempoLife › Brain and reaction tests › reaction-time
Reaction time
A reaction-time test measures the gap between a signal appearing and you responding — tap when the screen changes colour. Simple reaction times are typically around a quarter of a second, though the exact number depends heavily on the device, your input method and your alertness.
These tests are for interest and self-awareness, not a clinical cognitive assessment. Scores swing with sleep, caffeine, stress, practice and your device. Persistent or worsening problems with memory, attention or thinking deserve a doctor's assessment.
Simple vs choice reactions
The quickest is a simple reaction: one signal, one response. A choice reaction — deciding which of several buttons to press — is slower because the brain has to select as well as react. Both are used in psychology, and both are affected far more by how awake you are than by raw talent.
Why the number is soft
Online reaction times bundle in your screen's refresh rate, input lag, and whether you are using a mouse, a touchscreen or a key. That means the absolute number is not very meaningful, but the change in your own score across a good night and a bad one, or morning versus late night, is telling.
What sleep loss does to it
Reaction time is the classic casualty of sleep loss. As you get more tired, "lapses" creep in — brief moments where you simply do not respond. Research has found that going roughly 17 to 19 hours without sleep can slow performance about as much as being at the drink-drive limit used in many countries, which is a large part of why drowsy driving is so dangerous.
Other tests
Memory span
How many items you can hold in mind at once — a window on working memory.
The Stroop test
Name the ink colour, not the word — a neat measure of attention and mental control.
"Brain age" tests
A fun score that bundles several quick tasks — take the number with a large pinch of salt.
Source: General cognitive-psychology references on reaction time, working memory, attention and sleep. Not a clinical assessment. · checked 2026-09-04
Frequently asked questions
What is a good reaction time?
Simple visual reaction times often land somewhere around a quarter of a second, but the figure varies a lot with equipment and method, so compare your own scores rather than chasing a number.
Why is my reaction time slower at night?
Alertness follows your body clock and your sleep debt. Late at night, and especially after a short night, lapses become more frequent and your average slows.
Track the sleep behind the score
TempoLife tracks your sleep and estimates the debt that slows your reactions and focus.