Eating foods that spike blood glucose and insulin before bed raises core body temperature and sympathetic activity, keeping the body in 'day mode'.

“Eating this before bed keeps your body on day mode, raising core body temp and sympathetic activity which delay melatonin release and reduces sleep.”

“the reason being is that those will actually just get translated more quickly into a sort of an energy and ultimately a heat index and when you need to fall asleep you need to drop your core body temperature so if you're fueling yourself with simple carbs right before bed let's say that you just have a nice big bowl of cereal sugary sort of nonsense you will actually see a slight increase in core body temperature because of that sort of sugar caloric burning that raises core body temperature that makes it harder for you to fall asleep”