Here's a familiar scenario. It's the day before a big calculus exam, and you haven't studied for whatever reason (short on time, too many other exams packed into the same day, etc.). Around 10 p.m., you finally sit down to review the calculus materials. Six hours later, you catch a short "nap" before rushing to school. You take the exam, and it seems to go fine. Although it wasn't your best effort, you pass and promise not to repeat the cycle when it's time for your next one.
This is what's known as cramming. And while students, parents and educators have long known it's not ideal, in desperate circumstances, it works to some degree. And by some degree, we mean it might save your GPA. But cramming doesn't provide long-term learning, according to Dr. Robert A. Bjork, distinguished research professor in the department of psychology at UCLA where he focuses on how we learn versus how we think we learn. (Spoiler: We are usually wrong.)
"[Cramming] can have pretty dramatic effects on the exam," Bjork says. "It will work in the sense of performance on an exam administered right at the end of cramming. [Students] get an impression that it really works, but it just works on the short term. It's accompanied with a dramatic forgetting rate after that." This is especially problematic when one lesson provides foundational information for the next, like in a math or language class.
Forgetting most of what you learned is not the only downside to cramming. Researchers have found that losing sleep while pulling an all-nighter also leads to residual academic problems for days after the cramming session. You can imagine the negative effects of an ongoing cycle of procrastination and cramming.