the house i stayed at in az. is only about 15 years old. i was sleeping in the den on a pull-out couch. at about 3 am, i woke up feeling vaguely uneasy and i actually thought someone might be in the room. about a minute after i woke up, the t.v. turned itself on. i turned it off and tried to get back to sleep. it took a while.
in the morning, i told my host and hostess about this and they exchanged a look but didn't say anything. that night when we were out to dinner, they told me that the previous owners of their house were two elderly sisters. one of the sisters had cancer and decided to kill herself by carbon monoxide poisoning in the garage. unfortunately, the gas killed both sisters.
apparently, lights and appliances turn themselves on and off at will in this house. the current owners, friends of mine who are not prone to believing in such things, chalk it up to the sisters and just live with it.
take this for what it is worth. it happened and i don't necessarily prescribe to the ghost theory but it was, for me, an odd occurrence. who knows.