Chills

So last night when I was laying in bed right when I was about to go to sleep I rolled over toward my bedroom door and then all of the sudden I felt a gust of wind hit me from behind almost as if someone left the bathroom window open I immediately turned around thinking that maybe something may have opened the window but to my surprise there was absolutely nothing it was extremely creepy. Any ideas on what can cause that? or how it is even possible to happen? if so please comment on this! thanks!