My worst college semester was as follows:
Physics (3 hour weekly lab, 2 hours of recitation, 3 hours of lecture)
Organic chemistry (3 hour lab, 3 hours of lecture)
Cell biology (3 hour lab, 3 hours of lecture)
Genetics (3 hour lab, 3 hours of lecture)
Biostatistics (3 hours of lecture)
Each of those lab courses had, as Farael said, prelab work for the procedures and lab reports (usually about 5 pages and then with pretty tables and figures to do as well). I was just a little overloaded.
I'm occasionally here at about 2 AM, mostly when I'm assigned to work odd hours. The 4 pm to midnight shift is irritating.
