" For heaven's sake, Potter! " said Professor McGonagall, straightening her glasses angrily (she had winced horribly when he had used Voldemort's name) .
This can end up causing Chvostek's sign, which is when facial muscles twitch after the facial nerve is lightly finger tapped 1 cm below the zygomatic process.
Involuntary twitching of the muscles around the eye has a number of causes including dry eyes, caffeine, bright lights, and just like during a tough workout, from simple fatigue.
The spontaneous firing of neurons also leads Chvostek's sign, which is when facial muscles twitch after the facial nerve is lightly finger tapped 1 cm below the zygomatic process.