Your ability to react quickly may do more than just help in sports or video games — it could reveal key insights into your overall health, from brain function to risk of early death, researchers say.
As we age, slower reaction times are to be expected, but how rapidly they decline could indicate deeper biological issues. According to scientists, reaction time is not just a reflection of reflexes but a comprehensive marker of how well various systems in the body are functioning together.
“Some people are naturally faster, but when reaction time declines, it’s often a sign of accumulated ageing across many biological systems,” said Professor Simon Cox, an expert in brain and cognitive ageing at the University of Edinburgh.
Reaction time can be measured at home through simple tests like the “ruler drop test,” where a falling ruler is caught between a person’s fingers, and the distance fallen reflects response speed. Results under 7.5 cm are considered excellent, while those over 28 cm may be a cause for concern.
Studies have linked declining reaction times to a higher risk of chronic illnesses such as coronary heart disease, stroke, and even dementia. One study found that slower reaction times were associated with higher all-cause mortality risk.
Importantly, experts caution that a single test result doesn’t paint the full picture. “What really matters is whether your performance declines significantly over time,” said Cox, who suggests taking the same test annually for a clearer view of neurological health.
Reaction speed depends on an intricate network of systems: sensory input (like sight and sound), brain processing, and motor function. All these components can degrade with age — and not always at the same pace.
Research at the University of Colorado Boulder has shown that even when the brain registers an event almost instantly, older adults may struggle to respond physically due to weakened muscles or less efficient mitochondria, the energy producers within cells.
Still, not all is lost with age. According to Professor Matthew Pain of Loughborough University, studies show the brain’s ability to send movement signals remains fairly intact in healthy elderly individuals. “The nervous system hardware is not drastically worse — it’s the body’s response speed that lags,” he noted.
Technological tools like reaction-based computer games or platforms like the Human Benchmark Reaction Time Test can also help track changes in performance over time. Sharp drops may signal the early onset of neurodegenerative diseases such as dementia, even before symptoms appear.
To keep your brain and body sharp, experts recommend dual-task training — exercises that combine physical movement and mental challenges. Walking while reciting the alphabet or tossing a ball while naming objects are simple yet effective examples.
Cox adds that staying intellectually and socially engaged — through board games, sports, or learning new skills — may also help preserve fast reaction times and slow cognitive ageing. “It’s all about keeping the mind and body challenged,” he said.
