For those of you who don't read my blog on a regular basis, I'm not the kind of person who thinks all hauntings are fake. Experience has taught me that fairly often there is actually something else causing phenomena that freaks people out, making them think their house is haunted when it really isn't. Just read on and you'll begin to see what I'm talking about.
Houses settle, both new and old, and everyone knows a settling house can cause all kinds of noises. You can sit in your house at night and hear the creaks and pops generated by the settling. Sometimes the settling can sound like knocking or footsteps, especially to someone who is easily spooked or half asleep.
Plumbing problems can also make noises some people mistake for ghostly activity. If a water pipe is not secured properly, it can shake or vibrate as water flows through it, making a loud knocking sound against a wall stud, etc. A leaking toilet tank can even make the toilet appear to flush itself (called phantom flush).
Rats or mice can actually make noise that sounds like footsteps. As the little rodents scurry through your house's subfloor they make noise that can cause you to think someone is walking in the next room or directly above you. Of course there are signs of rodent activity, such as chew marks on your walls, ceiling or floors as well as droppings.
Natural gas leaks can cause people to hallucinate, under the right circumstances. Gas companies put a scent in the gas so you can detect a leak, or you can buy a natural gas detector if your nose is usually plugged up (or you have a really poor sense of smell). Natural gas leaks can lead to other health problems, as well as cause explosions or house fires, so once you know of a leak contact your gas provider immediately.
Interestingly enough, high levels of radon (which naturally emits from different parts of the earth) have also been shown to cause hallucinations. You can buy a test kit at your local hardware store to test out this possibility, since there are no positive signs of a high radon levels. Radon is also tied to cancer, so it is definitely worth testing for.
Hallucinations can also be caused by poor electrical wiring in homes, some people think. This is one reason why some ghost investigators carry electric field detectors with them. There is a healthy chicken-or-the-egg debate about electric fields, with some paranormal investigators arguing that ghost activity is the origin of some strong electromagnetic fields. Scientists have argued that the electrical fields can stimulate different parts of the brain to cause a person to hallucinate, such as getting the feeling someone is standing behind them.
Finally, some "hauntings" are the result of someone who has a real psychological disorder. I have run across this before, not with me but with other people who have contacted me. Most of these people experience the "haunting" wherever they go, including while driving. If you are experiencing a haunting and are afraid that people will think you are crazy, you should know that everyone I ran across who had that fear seemed psychologically well-adjusted. Of course I am not a psychologist, so that is just in my opinion.