By: Cindy Wooldridge

In earlier blog posts we have discussed the benefits of sleep, spacing, and retrieval practice on long-term retention of information. As a (very) brief refresher, all three of these strategies increase the storage strength of information that we have studied in ways that are quicker than traditional strategies (e.g. re-rereading). Imagine the excitement of the learning scientists team when a study was published looking at all three at once!

Last month, Stephanie Mazza and colleagues published a paper (1) looking at the interaction of sleep, spacing, and retrieval practice to see if combining these strategies could lead to better learning. Here’s what they did:

All participants learned 16 French-Swahili word pairs, which looked something like this:

Chat-Paka

Bateau-Mashua

First they read all 16 word pairs and then they were given a test where they saw one of the words and had to type in the correct pair:

Chat-______

If they got it wrong, they were shown the correct answer and that item was tested again later. If they got it right, they didn’t see it again. They kept testing until they had gotten all 16 correct.

Participants were then divided into three groups:

• Sleep Group: Studied the word pairs at 9 p.m. and came back to take a test at 9 a.m.
• No Sleep Group: Studied the word pairs at 9 a.m. and came back to take a test at 9 p.m.
• Control Group: Studied the word pairs at 9 p.m. and came back to take a test at 9 a.m (see below for the difference between Control and Sleep groups).

When the Sleep and No Sleep groups came back, they took a test to see how much they remembered and then went through the same procedure as before, being tested on all of the items until they got them all correct. The Control group simply took a test without relearning the items that they missed. Finally, they tested participants after 1 week and 6 months to see how much they remembered. 

Participants were also tested on their quality of sleep and both their short-term and long-term memory function and all three groups scored similarly on all measures.

Here is how each group performed over time:

1) The two groups who slept after training (Sleep and Control) remembered a lot more after 12 hours than the group who did not sleep. Sleeping after learning leads to consolidation.

2) Relearning after sleeping led to even bigger gains after a full week! Sleep helps with consolidation and also additional learning.

3) By combining spaced retrieval practice with sleep, students remembered twice as much as long as 6 months later! Combining sleep with other learning strategies has extra retention benefits.

In addition to these awesome results, the researchers also found that the Sleep group took fewer trials and less time to reach successful retrieval of all 16 words than did the No Sleep group. As the authors put it:

So, overall, the data showed that if you get a good night’s sleep, you will remember more of the material you studied, have a quicker and easier time relearning the material you forgot, AND if you take the time to relearn, you’re more likely to remember that information for much longer if you slept in between study attempts.

How can students use this new information to improve their studying?

1) Sleep!  … no really. Getting a good night’s sleep throughout the semester (including both immediately after learning the material and the night before the exam) will improve your grades. How much easier can studying get?

2) Space out your study across multiple days. If you do all of your studying the night before an exam, you’re missing the HUGE boost that comes from relearning that material. Even if you’re going to cram, make sure you cram before and after some sleep. (Maybe even take naps during a study session!)

3) Space out your study across the entire semester, and practice retrieval. Every time you sleep after studying and every time you restudy/retrieve after sleeping, you gain additional boosts and make the restudying process faster and easier. Even if you only do this occasionally, you will make your life easier when it comes to final exams because the effects last for at least 6 months!

References:

(1) Mazza, S., Gerbier, E., Gustin, M., Kasikci, Z., Koenig, O., Toppino, T.C., & Magnin, M. (2016). Relearn faster and retain longer: Along with practice, sleep makes perfect. Psychological Science. Online first, doi: 10.1177/0956797616659930.