My heart starts beating very fast and the beats are very light. i have reached 180 bpm and it is often triggered by caffeine. other times randomly.?

Be seen: That is certainly abnormal, and needs to be evaluated by a cardiologist. Stay off the caffeine in the meantime.

Possible arrythmia: If this is happening outside of vigorous exercise you may have an arrythmia and should be evaluate by your physician. While caffeine may trigger it sometimes, caffeine alone does not usually cause that high of rate. See your doctor!