if you are getting only 6 hours of sleep, it's pretty unlikely you will be able to lucid dream if you are not an experienced lucid dreamer. like almost everything else worthwhile in life, in order to succeed in lucid dreaming you have to spend a lot of energy, time and patience. if it's not possible to alter your sleep schedule right now, work on the other aspects of lucid dreaming-- get used to doing reality checks, work on dream recall--and maybe after AP tests (in may, right?) you will have a really solid base to start putting the actual dreaming aspect into practice.