It is likely that more than one theory is valid, but I believe that the Restorative Theory is the main one. During NREM sleep, the body physiologically restores itself, while during REM sleep, the body mentally restores itself. Cell division and protein synthesis increase during sleep. Many growth hormones are released while the body is asleep. Mental and intellectual growth can occur from neuron pruning, which happens during sleep. All this evidence suggests that the Restorative Theory is the most applicable.

Ghosts are not real, although I am open to valid evidence of them. From what I have seen, the "proof" of ghosts has had flaws. A lot of explanation comes from religion, and it is invalid to argue using religious beliefs. The media also affects people's perspective and makes them believe that they are real. They may become paranoid and claim that their experiences are caused by ghosts. People naturally come to conclusions because they do not like confusion. As I said, I am accepting of new evidence that shows that they are real, but as of now, I do not believe ghosts are real.