Ghost in my bedroom

I had a horrifying experience yesterday night, i was awakened by this strange feeling of bed sheet trying to wrap me tight ! I couldn't release myself and somehow i managed to jump out of the bed. I looked at the bed and i found that the bed sheet was now frizzled like a think rope ! I switched on the light and saw that the time was 2.45 AM. I just wanted to make sure i was dreaming, i turned on 93.3 FM, it was Dylan playing "Knocking on the heaven's door" and i could hear it quite clearly! After a glass of coke, i decided to go back to sleep, this time with the radio on

Still i am not sure whether it was some ghost's trick or a wild dream ;-)