Cramming: Skipping sleep for short-term gains

Most “professional” students will at some point find themselves in situations where the amount of material they need to learn far exceeds the amount of time they need to prove mastery. In this mini series, we will explore a couple of the factors at play, and how to tip the scales in favor of durable knowledge and the most efficient (and fun!) ways to achieve it.

In Part 1: The “Perks”, we discussed some of the reasons we’re drawn to cramming. Research shows that cramming can lead learners to feel more satisfied. What’s the catch?


Part 3: The Fluency Fallacy

Cramming material means studying everything in a short amount of time. This rapid-fire method engenders a feeling of fluency, because the material never actually has a chance to fade from short-term memory. Think of short-term memory as the part of your brain that allows you to remember a phone number after someone’s called it out to you from across the room. It keeps it in your mind just so, and you can probably recite that phone number on cue...for a little bit. But after a while, your short-term memory passes that information to your long-term memory. The most durable knowledge has been repeatedly retrieved and restored in your long-term memory through a mechanism called reconsolidation, so much so that your mental representation of that memory is permanent. Therefore, to form durable knowledge, it’s essential for information to have the time to shift from short-term memory to long-term storage before being retrieved again. 

Unfortunately, spacing apart study sessions or increasing the interval between retrievals (aka “lag”) can make learners feel like they have a poorer grasp of the material. The lag also exposes weaknesses in understanding that otherwise might have been masked. Lastly, retrieval from long-term memory is inherently more effortful. 

Understandably, the fallacy of fluency is one reason why we might actually feel good about cram sessions before exams, even when pulling all-night study sessions. While there might be increased fluency for the immediate time after study (even resulting in better test scores), learners will not benefit from the cataloging of memory into long-term memory, especially since sleep is critical for consolidation. For serious learners, late nights are truly poor investments of time. 

At the end of the day (or night), a little faith in the science supporting spaced retrieval can guard against the feel-good feelings that come from the fluency of cramming. 

Next week: Cramming can get you better test scores, which is extra appealing in today’s high-stakes exam environment. Here’s why you should resist the temptation.

P.S. Here’s a TED talk that helps us understand sleep as an extension of learning and memory: