I'm asking this on behalf of my aunt, who has mental and speech disability. She is about 45 years old, but her mental age is that of a 10-12 year old. She, however is active and is completely capable of taking care of herself. Since about a month or so, she has been complaining that she hears a very loud noise in the night, making it very difficult to sleep. Any lead as to why it happen and if should we be worried about her present condition.