Be VERY careful if you ever decide to go on a "Ghost Hunt". Sometimes, spirits are able to attach to you and that's when all Hell breaks loose in your life. There are some spirits who "Feed" off of the energy you emit while under stressful and fearful situations. You could call them spiritual vampires. Some people experience them as "Shadow People". They are the ones that cause night terrors or sleep paralysis. Be VERY careful and always protect yourself. If you are there and you show or feel fear, you will light up like a beacon to them and they all flock straight to YOU. They see you as a free "fix". It's like a drug to them.
Demons can disguise themselves as anyone they want and they can make you believe, even swear you are talking to your dead Great Great Grandfather or someone else you know. Once you start communication, they attach. It's like giving consent.
Read in the Bible about King Saul and the Witch of Endore and what happens to people who communicate with the dead. "Necromancy" and "Sorcery". Sorcery is basically drug use. It's translated as "Pharmakaea" and means drugs. They can open up doorways to communicate with the dead. Some "Drug induced hallucinations" are NOT hallucinations.
Sleep paralysis also occurs every time there is a UFO abduction reported. I believe "Aliens" are the "Demons" and "Angels" of the Bible. I was once writing a book on my theory about 18 years ago and I think I got too close, because... A LOT of crazy things started happening when I was writing that book. I stopped writing it but it was too late. My life fell apart before my eyes and there wasn't anything I could do about it.