The vagus nerve plays a role in (amongst other things) controlling the pulse. The vagus reflex is a reaction which can reduce the pulse rate during tachycardia (racing pulse). The following stimuli may produce the vagus reflex:

- tensing the lower abdomen (imagine how it feels when you go to the toilet)

- gentle pressure on the closed eyes

- a gulp of ice-cold water

- splashing ice-cold water on the face

- immersing the arms in ice-cold water

- finger stuck down the throat

- the insertion of an IV needle