Dani: Depending on where you felt the pressure of something walking on you it may have been Sleep Paralysis. It's a sleep disorder that occurs when the mechanisms in your brain that allow you to dream and the ones that keep us from moving while we sleep are active at the same time. Most people who suffer from it report feeling pressure on their chests as if someone is sitting on them. Auditory and visual hallucinations are also commonly reported.
Night Terrors is another sleep disorder that can cause similar symptoms as to what you described. People are often jolted awake by something frightening but then can't remember what, only that they're awake and scared. I'm told that it's a lot harder on the partner of the person with the night terrors as they often wake up screaming and crying for no apparent reason.
I'm not afraid of the Dark, I'm afraid of what's IN the Dark. ~Anonymous~
Ball Python, Leopard Geckos, Bearded Dragon, Crested Geckos, Corn snakes a Dumeril's Boa and African Dwarf Frogs so far.