The looping dream is where you dream one dream for what seems like the entire night - and wake up constantly, only to fall back asleep into the same dream. Unlike that really good dream that you get woken out of and try unsuccessfully to get back into, this is a dream that you want to escape but you just can't. You may not necessarily have trouble getting back to sleep, but your quality of sleep suffers because you fall in and out of sleep and while you're sleeping, you're trying to wake up out of the dream.
Normally, this repeating dream is caused by your not being able to clear your mind (one of the points mentioned in my ebook 39 Ways to Guarantee your ZZZs) before bed. Or it may be something trivial that you may have heard or talked about during the day.
The problem with the looping dream is that it causes you to repeatedly wake up during the night and severely affects the quality of your sleep.
So, what should you do if you are experiencing the looping dream? Get out of bed. You need to disassociate yourself with the environment where you are experiencing the looping dream. Just moving to the couch or sofa should be enough to snap you out of the cycle.
And when you move to the couch and try to fall back asleep, make sure that you think about something entirely different before drifting off to sleep. If you are on the sofa, it's possible that there will be some sounds that you'll be able to hear throughout the house. It may help to focus - ever so intently - on these sounds. Focus to the point that you are concentrating on one sound alone. If you concentrate on that one sound, you'll force your mind to block out all other thoughts and that, coupled with your new sleep environment, should allow you to drift back to sleep without ending up in the same looping dream.