We pulled an all-nighter to answer this one.

Hey:

Settle an argument with my friend. He says cramming for an exam doesn’t work. I say staying up all night studying and going right into the exam makes the information fresh in my brain just long enough to take the test. What do you say?

-- B Average, San Marcos

I say, if you’d listen to your friend, you could be a Rhodes Scholar. Then you’d get to hang out with Bill Clinton at reunions. But if you’re just a B kinda guy, happy to breeze along with the occasional all-nighter, then read no farther. Three sentences may be your limit anyway. But don’t take my word for it. They’ve actually studied this very question at Harvard Medical School, and I’m sure the shrink who ran the tests got plenty of shut-eye.

Two groups of subjects were taught a new skill and given plenty of time to practice. Then one group hit the rack and the other sat out by a freeway all night or something like that, still practicing. The well-rested students performed way better than the other crowd. But the results had nothing to do with fatigue, sez the science guys. According to the chief inquirer, sleep is critical to the formation of memories, which is basically what learning is. After a bout of studying, they say, a bare minimum of four hours of sleep will give your brain a chance to tidy up and put all those facts in brain slots where you can get at them.

The first two hours, when we’re in very deep sleep, brain chemicals “move” all those shiny new facts into our brain’s cortex, the site of long-term memories. Hours two through four, the brain sorts through all the tripe and files it in appropriate cranial cubbyholes. Nerve cell links are solidified, and the place starts to look pretty organized. If we can manage hours five and six of rack time (REM/dream sleep), our brains use that to shuffle back through the night’s work and process it. Sounds a little like working for the post office.

The problem with all-nighters is that whatever you’re trying to cram into your headbone never makes it to a place where you can retrieve it easily. You derail the chemical process of memory storage. Use this as ammunition when you doze off in class.