You should always make time to rest. Even when you are at your busiest moment in time, you still need rest. You won't be able to function 100% unless you have proper rest and you've eaten food. Don't try to force all that work in one sitting. Break it up into parts. Even if you have to work an hour and rest for 15 minutes for a full day, a 15 minute power nap can be all you need to get through the rest of that work! Then once you finish with your allotted work for the day, get a good nights rest and then do the same process all over again the next day. You won't feel as tired and you get all your work done with less mistakes and more proficiency!