<chuckle> Oh dear, sorry Ivana! The “50" refers to 50 mg/ml blood glucose reading, which we diabetics get off a glucometer after pricking our finger to get a drop of blood. Below a reading of 80 is usually considered hypoglycemic — low blood sugar.
Our bodies and brains react differently, depending on person and circumstances, but for me, a reading in the 50s or below means a certain mental slowness. Sometimes I also have body shakes, sweating, and I have to spend mental effort on breathing. It’s often unpleasant enough to wake me from a sound sleep. If I am awake I can feel the effects before it gets too low, and I keep a food bar or hard candy with me at all times when away from home.
So at 04:30AM, if I am awake it is because I am trying to get my blood sugar back to normal by eating something with sugar or simple carbohydrates. Then I go back to bed!