Is it normal to start having regular strong contractions (1 hour apart) and then suddenly stop after 6 hours?

Like what Nooraini said, what you are experiencing sounds like prelabor. They occur before first stage labor really kicks in and can start as early as two or three weeks before or could also start a day or two before established labor. Prelabor is preparation time for the body and the baby. Prelabor contractions work toward shortening (effacing) and widening (dilate) the tube-shaped cervix and stretching the bottom of the uterus. The contractions also soften the cervix. Prelabor primes the cervix very well so that once established, labor starts the progress and it can be quite quick. Take care! Stay hydrated and well nourished during this period to help the body build up strength and energy to cope with the upcoming labour. All the best!!