Good question, my dad always used to tell me this, here's what happens eating right before sleep causes you to fall into deep sleep very quickly, but here's what happens because are asleep so soon after eating, your body has no time to digest the food until you are at a stage 1 sleeping state, right before you wake up.
The dreams you remember all occur in stage one, you essentially have hundreds of dreams a night but the only ones that you remember and see vividly occur at stage one.
Stage one therefore is prolonged when eating right before because your body wants to digest while you are resting and it has a lot of food to digest because it hadn't had a chance to digest it earlier.