My friend keeps seeing ghosts. What is this about?

I personally do not believe in ghosts; but, for the folks who do claim to see them, I believe them when they say so. Here's an article I found in Psychology Today about the subject which might help you and your friend. Here's the blurb from the article:

"Geomagnetic fields may be the real reason people see ghosts when they go to bed. A sensitive temporal lobe-the area that is responsible for regulation of emotions and motivated behaviors-together with naturally occurring magnetic fields, can trigger a ghostly encounter."

See the link below for the rest of the article:

Ok well she may be lying but since i have visions and sometimes see them im going to trust you and her >.<. She may have a supernatural power and they need her help, they need to cross over so since she has that power she can help them. If she doesnt want them around her all she gotta do is dont be afraid of them, as some evil or others feed off fear. Also let a pastor dude bless her house to keep them away from there. (I Hope That Was Serious Enough Cause I Aint That Serious :D) ~ Hopey I Helped!!

It depends. If they are acknowledging her, most likely. If not, there is a possibility that she is a psychic medium.