Three. The ordinary physical things

Caffeine produces heart rate changes and jitteriness that are close enough to the alarm to be read as the alarm. Four coffees in and your body is already halfway there before anything happens.

Sleep loss lowers the threshold on the whole system. So does alcohol, which quiets it at night and hands it back to you with interest at four in the morning.

None of this is the cause and none of it is the cure. It is the part you can change tonight without needing an insight.