It's sleep paralysis! Something not to worry about. Physically it is not harmful, but it can be very stressful at times (especially when you don't know what it is- I thought I'd went into a coma the first time I had it!)

Google "sleep paralysis"

-Dreads

Classic symptom of sleep paralysis. I've suffered with it since I was around 9yrs. old. Honestly, I have trouble believing that millions of people all over the world are having the same basic nightmare. Also, it's said that our brain wakes up before our body and that our body goes into a state of paralysis during sleep so we don't physically act out our dreams. Hmmmm, I know many people who toss, turn, or make complete circles while sleeping. Also, people talk in their sleep all the time, so I just can't buy that explanation. I wonder if it isn't the secret government messing with people during their sleep. Sound crazy? Google government secret experiments and you can find all sorts of crazy things they've been doing to us.