Im in my second year now and have only ever worked until about 1 reading. Though some of my friends have stayed up all nights doing essays and seminar work, but they are unorganised!
If you plan your time and don't waste time, then you will be fine.
I try to work 9-6 week days, with lectures in the day, then perhaps a few hours reading at night. Then about 5 hours Sat n Sun. This gives me the evenings free to relax, go out and do my sports!