Out of interest - do you suffer from asthma or other chest issues?
Some theories about dreams suggest that our dreams are the way in which we deal with 'day to day' problems or worries. This means that they manifest in a way that reflects the 'emotions' and 'experiences' of the actual issue - this allows our brain to work a way of solving the problems while we sleep.
The explanation (boring bit). When we have a stressful event, it is often a part of the brain called the amygdala that 'kicks in'. This part of the brain is not capable of rational thinking. A good example is when we are arguing - how many people have said something they really wished they didn't at this time. It is because the amygdala was being used. Our 'rational thinking' part of the brain is the cortex. So, during our sleep, the brain is trying to 're-live' stressful situations by using dreams, and this will allow us to solve the issue by getting it back into the cortex. Recurrent dreams mean that we haven't yet solved the problem.
Ok, boring bit over. So, if we follow this theory, then it might suggest that you have a worry relating to your chest or breathing
Gary (agony uncle)