Midterms and finals suck, especially when they are condensed into a week. Knowing how most students work and having been one of them; people usually tend to procrastinate and start working at the last possible point which can usually be calculated too optimistically. :)
The human brain is the most demanding organ in terms of energy, so if you want it to work well for you, you have to work well for it first. Let's see how we should feed our beloved brains!