The time it takes for our bodies to respond to something is known as reaction time. This is our brain’s ability to detect and process a stimulus and our body’s potential in reacting to it. To understand how this process works, it’s best to see reaction time as a sequence of three key stages. These are:

1. Perception: Seeing, hearing or feeling any kind of stimulus. For example, becoming aware that your phone is ringing. 

2. Processing: The cognitive operation of understanding what the stimulation is and processing that information. For example, realising that your ringing phone needs picking up to be answered.

3.
Response: Reacting to the stimulus in question and with enough motor agility to act with a good response time and fulfil your brain’s request. For example, moving your hand to pick up the phone. 

If any stage of this process is modified, there will be a knock-on effect to the reaction time. 

There’s a whole host of factors that reaction time depends upon, some of which are more permanent, while others are temporary. Age, level of physical fitness, general diet, and even personality type are the more permanent factors, while temporary circumstances can include current mood, tiredness and level of caffeine or alcohol in the system.