Can anyone explain why I'm hearing voices and having nightmares?

I will say firstly that I'm not in any way crazy or deranged! but in the past week I've been hearing voices in my ears/talking as I'm drifting off. Last night I was half asleep and was awoken with a loud laughing in my ear and it completely freaked me out! I've also had a two bad dreams this week in which I feel an evil presence and the first time I woke my husband up with my screaming. It felt like there was something there shaking my bed backwards and forwards. A few days ago was the worst and I was determined and conscious in that dream that I wanted to wake up because it felt so evil and each time shouted until I woke up. I was determined to stay awake but kept drifting off into the same dream and each time able to wake myself up. This went on for about 2 hours. I know I sound mad but I'm a happy stress free (well almost with 2 boys!) person but my nan's a spiritualist and often has experiences so I was wondering whether I'm tuning into something paranormal