We’ve all done it, haven’t we. There was an meeting exam looming and, for one reason or another, studying just didn’t happen in a timely manner. So cramming ensued and the exam was taken in a caffeine haze. But what happens to the memory of that biological pathway stuffed into your brain in a panic-frenzy at 4:45am? Odds are it doesn’t stick around much longer than the exam period…if that long. But why how?

Susumu Tonegawa and colleagues at MIT’s Picower Institute for Learning and Memory have demonstrated some molecular reasoning for how sleep is critical for the formation of long-term memories. In a study that is to be published tomorrow in Neuron, the authors show that, during sleep, mice “consolidated” short-term memories into long-term ones by “replaying” decisions made during the negotiation of a maze. They found that this process was entirely reliant upon a particular hippocampus circuit (the trisynaptic pathway) and without this functionality, the memories of the day were not consolidated during sleep. As a result, long-term recall of those same memories was impaired.

So if an all-nighter is unavoidable because of perhaps ill-considered extracurricular activities, get some sleep as soon as you can and maybe some of that information will still be around for the quarterly presentation final.

To take a look at the work itself, you can go here (subscription, institutional or otherwise, required).