CA to NA

I started working at a care home/long-term facility about a month ago as a care assistant(help serve meal/set up trays, change beds, wash water pitchers, do food/fluid intake), which is basically helping out the nurses as much as possible without touching the resident. I do an earn and learn program so I start off as a CA then take classes to become a CNA. 

I started my classes recently, they start in the afternoons from 4:30-9:30. I also work in the mornings from 6-2:30. Of course I love my job and I love the fact I have the opportunity to become a CNA through my work. However, I have become so exhausted to the point I start to fall asleep at work or I do my work while slightly light headed, kinda like if I was floating, and I haven't eaten much because of this schedule either. 

It's only the first week, but so many people(coworkers and family) have noticed how tired I look and that I haven't eaten/gotten skinnier. I'm not too sure if I should ask my boss if I could postpone taking the class until after the holidays or after a new CA comes in so I wouldn't have to worry about the work schedule(if that makes sense), or if I should just get it over with.