We usually eat midnight snack after eight or nine o'clock, and it's time to go to bed after midnight snack, which means that the food added to midnight snack will stay in the stomach for the night, so that the stomach can't rest. Secondly, after we go to sleep, the body's demand for energy is very low, and the energy generated by supplementary food can easily accumulate into fat.
Generally speaking, I think midnight snack is unhealthy.