reconsidering my degree

hello, 19M science student here, entering into second year.

i've always wanted to do science and recieved decent scores last year, i'm majoring in biomed with plans of moving into post grad med.

however the restaurant i work at recently offered me a payrise in return for becoming a trainer. it would mean working a few more shifts each week, often quite late (til 10pm or so) and i'm thinking it could seriously jeopardise my degree if i did both. it would suck to drop out after such a successful year, but i've been working at mcdonalds for years now and the pay has gotten pretty good (with the crew trainer offer i would be paid 50c extra per hour).

what do you guys think?