How to improve reaction time: simple and choice reactions, what training, sleep, caffeine, age and screens change, reactions in sport, and when slowing needs a check

About a fifth of a second

For a simple visual signal, adults react in about 0.21 to 0.23 seconds on average. With more possible signals and responses it takes longer, and longer again with each extra option.

Sources 1, 2

You get faster at what you practise

Light, app and device drills make you faster at the drill. Whether that carries over to your sport or daily life is mostly unproven.

Sources 3, 4

In sport, reading the cue is what trains

Experts react faster mainly because they read cues earlier, not because their basic reactions are quicker, and video training that teaches you to read opponents carried over to the field.

Sources 5, 6, 7

Sleep is the biggest lever

A night or two without sleep slowed reactions by a moderate to large amount, and two weeks of 6-hour nights was as bad as up to two nights without sleep, without people noticing. The NHS says adults need 7 to 9 hours.

Sources 8, 9, 10

Caffeine, exercise and games help a little, or not at all

Caffeine gives a small speed-up and a session of exercise a small, short-lived one. Video games speed you up in lab tasks, with no good evidence for sport.

Sources 11, 12, 13

Sudden slowing is an emergency

Slowing that comes on suddenly with weakness, a drooping face, slurred speech or loss of balance is a 999 call. Slowness, stiffness or a tremor that builds over weeks or months needs a GP.

Sources 14, 15

Reaction time, movement time and reflexes

Reaction time is the delay between a signal (a light, a sound, a ball leaving a racket) and the start of your movement: noticing it, deciding and sending the command to your muscles. Movement time, finishing the movement, comes after. A reflex, such as pulling your hand from something hot or the knee jerk, skips the decision, and it isn't what training changes (our explanation).

Simple and choice

Simple reaction time is one signal and one response: about 213 to 231 milliseconds for a visual signal in adults. Choice reaction time has several possible signals and responses, and gets longer with each extra option. Most reactions in sport and driving are choice reactions.

Sources 1, 2, 5

Typical numbers

Simple visual reactions take about 0.2 seconds in adults. Athletics' false-start rule assumes no one can react to the gun in under 0.1 seconds, but in 9 sprinters, a fifth of starts in two of the test conditions were faster than that. Older people who had fallen took about 1.3 seconds to step onto a lit panel, against 1.2 seconds in those who hadn't.

Sources 1, 16, 17

Age and sex

In 7,130 UK adults, simple reaction time changed little until about 50, while choice reaction time slowed gradually throughout adulthood. In 1,469 people aged 18 to 65, simple reaction time rose by about half a millisecond a year, mostly in the movement part rather than the thinking part. Differences between men and women were small or absent.

Sources 18, 1, 19

A home test

The ruler-drop test is a rough measure used in studies: a partner holds a ruler between your thumb and finger and lets go, and the distance it falls before you catch it converts to a time. Online tests vary with your screen and device, so use the same method each time and compare yourself with yourself (our suggestion).

Source 20

Typical timesStrong evidence

In 1,469 adults aged 18 to 65, simple visual reaction time averaged 231 milliseconds (213 after allowing for equipment delays) and rose by 0.55 milliseconds a year. In 7,130 UK adults, simple reaction time slowed little until about 50 and choice reaction time slowed throughout adulthood.

Sources 1, 18

More choices, slower reactionsStrong evidence

Choice reaction time rises with the number of possible signals and responses (Hick's law), with exceptions for well-practised and very natural responses.

Source 2

Experts read cues earlierStrong evidence

Across 42 studies, experts picked up sport cues more accurately and faster than non-experts, with fewer, longer looks. Across 142 studies of 8,860 athletes, higher-skilled players stood out more on sport decisions than on general thinking tests, and athletes also did better than non-athletes on lab speed tests, most in sports where you intercept a ball.

Sources 5, 6, 21

Training to read opponents carries overEmerging evidence

In 12 studies of video training that stops just before an opponent's action ends, anticipation improved by a large amount, including on field tests. Sport-related visual training improved decision speed in 27 small trials.

Sources 7, 22

Reaction drills improve the drillMixed evidence

Light-based drills improved the trained reaction tasks in 24 racing drivers and 31 older adults, and reactive drills sped up choice reactions in 40 young table tennis players, though by the end not significantly more than planned drills. Of 43 studies of commercial training devices, only 1 tested a sport task, and tracking training didn't improve game performance in 62 academy footballers.

Sources 3, 23, 24, 4, 25

Slower reactions go with poorer healthEmerging evidence

In UK adults followed for 19 years, slower and more variable reactions were linked with a higher risk of death, partly explained by health and social factors. That's a marker, not proof that training your reactions adds years.

Sources 26, 27

Sleep lossStrong evidence

Across 70 studies, 24 to 48 hours without sleep slowed reaction times by a moderate to large amount. In 48 adults, two weeks of 4 or 6 hours in bed caused steadily growing deficits: 6 hours or less a night was as bad as up to 2 nights without sleep, and people were largely unaware of it.

Sources 8, 9

Sleeping moreEmerging evidence

In 11 college basketball players, aiming for 10 hours in bed for 5 to 7 weeks added about 110 minutes of sleep a night and sped up a reaction test, sprints and free throws. Only 2 such studies exist in athletes, so it's promising, not proven. The NHS says adults need 7 to 9 hours.

Sources 28, 29, 10

CaffeineStrong evidence

In 31 trials of 1,455 people, caffeine made reactions slightly faster, a small effect, more at doses of 200 mg or more. It doesn't make up for poor sleep (our reading).

Sources 11, 30, 31

How much caffeine is safeStrong evidence

The European Food Safety Authority says single doses up to 200 mg, and up to 400 mg a day from all sources, are of no safety concern for healthy adults, and that 100 mg close to bedtime may affect sleep in some adults. In pregnancy, the NHS says to have no more than 200 mg a day. The NHS puts a cup of instant coffee at about 100 mg.

Sources 32, 33

ExerciseMixed evidence

A session of exercise gave a small, short-lived lift in thinking speed across 383 studies, whatever its type or length, with moderate intensity helping speed most. Longer term, aerobic exercise didn't speed up thinking in healthy older adults in a Cochrane review of 12 trials, while a network analysis of 110 trials found mind-body exercise such as tai chi and yoga helped processing speed most.

Sources 12, 34, 35, 36, 37

Video gamesMixed evidence

Action games shortened lab reaction times: 50 hours of them cut reaction times by 13%, against 6% with other games. But published effects are about 30% larger than the full body of research, a large review found no evidence that game training improves wider thinking skills, and we found no good study showing gaming speeds up reactions in sport.

Sources 38, 39, 40, 13, 41

PhonesStrong evidence

Using a phone while driving slowed reactions by about a quarter of a second, with hands-free calls as bad as handheld, and texting made it worse; it's illegal to hold and use a phone while driving in the UK. One study linked longer phone use before bed with slower reactions in students; we found no review of screen time and reaction time.

Sources 42, 43, 44, 45, 20

Read the cues

Watch the opponent's hips, shoulders and racket or kicking leg, not only the ball, and use video of your sport: training on video clips that stop just before the action ends improved anticipation on the field. Your coach and our sport pages have the specifics.

Sources 5, 7

React and moveEmerging evidence

Drills where a partner or a ball decides the direction, and small-sided games, improved reactive agility mostly by speeding up decisions, as our agility guide explains.

Sources 46, 47

Starts

In sprinting, the gun is a simple reaction: practise starts to a partner's clap or a starter, and keep the rest of the session as our sprint guide sets out.

Source 16

Sleep first

Aim for 7 to 9 hours. Short nights add up, and you won't feel how much they slow you.

Sources 10, 9

Practise the reactions you need, in context

A partner's cue for cutting, a ball for catching, an opponent for anticipation: 2 or 3 sessions a week of 10 to 20 minutes alongside your sport (our editorial starting point; the drill trials used 2 to 3 sessions a week for 6 to 8 weeks).

Sources 23, 24, 4, 46

Warm up before you need to be sharp

A session of moderate exercise gives a small, short lift; our warm-up guide has the routine.

Sources 12, 35

Put the phone away

When you need to react (driving, cycling, crossing a road), even a hands-free call slows you.

Sources 42, 45

How long it takes

Drill trials ran 4 to 12 weeks. You'll be faster at a drill within a few sessions, but that isn't the same as faster in a game (our reading).

Step trainingStrong evidence

Practising quick steps in different directions to a cue improved stepping reaction time and halved the rate of falls in 7 trials of 660 older adults, and a home stepping game cut falls by 26% in 769 people over a year. Slower stepping to a cue went with falls in 477 older people.

Sources 48, 49, 17

Where to start

Next to a counter: side-steps, steps back and step-ups, then stepping quickly in the direction a partner calls, 2 or 3 times a week within strength and balance training (our editorial starting point). Our older adults and balance guides have the falls programmes.

After a head injury

Feeling slowed down is one of the thinking symptoms of concussion that our concussion guide lists; it covers the graded return to activity and sport.

Parkinson's or MS

Our Parkinson's and MS guides cover exercise for each, including balance and quick stepping.

Sleep problems

See a GP if changing your sleeping habits hasn't helped, you've had trouble sleeping for months, or it's affecting your daily life, as the NHS advises.

Source 10

Caffeine in pregnancy

The NHS says to have no more than 200 mg a day.

Source 33

Before hard partner drills

Speak to your GP first if you haven't exercised for some time or have medical conditions or concerns, as the NHS advises. Get advice before hard, explosive or straining work if your blood pressure is uncontrolled (140/90 or higher at a clinic, or 135/85 at home), or you have heart disease or chest pain when you're active, a pacemaker or defibrillator, diabetic eye disease, glaucoma, a hernia, recent eye or tummy surgery, or you're pregnant, as our breathing guide lists.

Sudden slowing with stroke signs: call 999 (911 in the US)

Call 999 (911 in the US) or go to A&E if you have sudden weakness or numbness in one arm, sudden loss or blurring of vision, or sudden problems with balance and coordination: these could be signs of a stroke. Call 999 too for chest pain that feels tight or spreads to your arms, neck or jaw, or severe difficulty breathing.

Sources 14, 15

The signs of a stroke

Call 999 if you think you're having, or have had, a stroke, or you've had signs of a stroke in the last 24 hours, even if they've stopped. The NHS uses FAST:

• Face: one side of your face may droop, and it might be hard to smile.
• Arms: you may not be able to lift both arms and keep them there, because of weakness or numbness in one arm.
• Speech: you may slur your words or sound confused.
• Time: call 999.

Slowed or confused after a knock to the head

Anyone who might have a concussion stops at once and doesn't play, train or do PE again for at least 24 hours. Get them assessed within 24 hours by a healthcare professional or NHS 111, and call 999 for red flags such as getting drowsier, repeated vomiting, a fit or a worsening headache (the full list is below). Fewer than 1 in 10 concussions involve being knocked out.

The UK guidelines call these red flags. They need urgent assessment, by ambulance if necessary. If a neck injury is suspected, only a trained healthcare professional should move the person.

• Any loss of consciousness, or getting drowsier
• No memory of events before or after the injury
• Increasing confusion or irritability, or unusual behaviour
• New problems understanding, speaking, reading or writing, less feeling, loss of balance, weakness or double vision
• A seizure, twitching limbs, or lying rigid or motionless
• A severe or worsening headache, repeated vomiting or severe neck pain
• A suspected skull fracture: a cut, bruise, swelling or severe pain where they were hit
• Previous brain surgery, a bleeding disorder, blood-thinning medicine, or being drunk or on drugs at the time

Source 50

After a head injury

Call NHS 111 if symptoms get worse or haven't improved by 14 days. The NHS says see a GP if symptoms of a head injury last more than 2 weeks, and the UK guidelines say anyone with symptoms beyond 28 days should stay out of sport and see a GP, who may refer them to a specialist. NICE asks that people whose problems persist are referred to specialists trained in brain injury.

Slowing that builds up: see a GP

Common reasons are weaker legs, less activity, medicines, low blood pressure, eyesight or hearing problems, and conditions such as arthritis, Parkinson's disease or a stroke. See a GP if it's new or getting worse, if you've had a fall, or if it comes with dizziness, hearing changes or numbness. Call 999 if it comes on suddenly with a drooping face, a weak arm or slurred speech.

Without a diagnosis

Our suggestion, from the NHS pages: see a GP if movements are getting slower with stiffness or a tremor, which can be signs of Parkinson's disease, or for daytime sleepiness or poor sleep that hasn't improved.

Sources 51, 10

Drowsy or distracted

Our suggestion: don't drive when you're sleepy, and don't hold and use a phone while driving, which is illegal in the UK.

Source 45

Stop and get medical help

If you get chest pain or pressure, feel faint or dizzy, are unusually breathless, or your heart races or beats irregularly during exercise, as our plans advise.

Call 999 (911 in the US)

For chest pain that comes on suddenly and doesn't go away, feels tight or like squeezing, spreads to your arms, neck, jaw, stomach or back, or comes with sweating, feeling sick, light-headedness or breathlessness; severe difficulty breathing; someone who faints while exercising; palpitations that don't go away, or come with chest pain, shortness of breath or feeling faint; or a headache that starts suddenly and is extremely painful, especially while lifting or straining, or comes with numbness or weakness, difficulty speaking or loss of vision. The NHS says a bleed on the brain may be more likely when lifting something heavy. Don't drive yourself to A&E.

Source 52

Check first

Speak to a GP first if you haven't exercised for some time, or if you have a medical condition or concerns. Get advice first, too, if you have a health problem, an injury or symptoms, have recently had a heart attack or an operation, or are pregnant or have recently given birth.

During any session

Stop straight away if you feel any pain or become unwell, the NHS says, and contact 111 if your symptoms worry you or don't go away.

"Reaction time can't be trained"Mixed evidence

Basic reaction speed changes little and drill gains mostly stay in the drill, but reading cues, which is what makes experts fast, trained well, including on the field.

Sources 3, 4, 5, 7

"Video games give you faster reflexes for sport"Mixed evidence

Action games shortened lab reaction times, but published effects are inflated, wider benefits are disputed, and we found no good study showing gaming speeds up reactions in sport.

Sources 38, 40, 13

"Reaction lights and apps transfer to your game"Mixed evidence

They improve the trained task; there's little evidence of transfer to sport, and a trial in academy footballers found none.

Sources 23, 24, 3, 25

"Your reactions slow down from your 20s"Emerging evidence

Simple reaction time changed little until about 50 in 7,130 UK adults; between 18 and 65 it rose by about half a millisecond a year.

Sources 18, 1

"Caffeine makes you much faster"Emerging evidence

The gain was small across 31 trials, and caffeine close to bedtime can cost you sleep, which slows you more.

Source 11

"Hands-free calls are safe while driving"Strong evidence

Hands-free conversation slowed drivers' reactions as much as handheld.

Sources 42, 43