Ghosts don't exist. Noises in the home at night are usually pipes and ducts, floorboards settling, or noise from neighbors that carries. Add in a healthy dose of human imagination and paranoia and you get people thinking they have ghosts.
Matter expands and shrinks when exposed to varying temperatures. What people have mistook for ghosts in the past we now realize has been this process taking place so tightly packed matter such as flooring or walls will press on itself and create these familiars noises. There are no ghosts. That is just in movies to scare you- it's pretty effective isn't it? Those movie folks know just where to strike to get your fear sensation a rumblin.