This is for
all of you that describe learning in college as pulling all-nighters cramming, being kept awake by extra-caffeinated Jolt
and loud, angry music courtesy of Rage Against the Machine. Have you ever wondered about the effectiveness of this technique,
ever had a hunch that it might be a tad bit counterproductive? A recent study conducted at Harvard Medical School, Visual
Discrimination Task Improvement: A Multi-Step Process Occurring During Sleep (Stickgold et al. 2000), suggests
it is imperative that college students sleep at least six hours after studying in order to learn new materials. Two very interesting
findings of the study were that the sleep must be for an uninterrupted sequential six+ hours at a time and sleeping a full
night after studying is “make or break” for long-term retention.
The Experiment: College
Students, Sleep, and Learning
In order to
understand the experiment, it is important to know two key terms: slow-wave sleep (SWS) and Rapid Eye Movement sleep (REM).
SWS mostly occurs early in the night and is characterized by relatively slow oscillations of brain waves on the brain activity
monitor. REM sleep occurs more toward the end of the night and is characterized by relatively fast oscillations of brain waves
(Maquet 2000). The researchers studied the sleep and performance on tests for 24 college students over three days. On the
first day, participants studied a visual image (think physics free-body diagrams and art history pictures!) consisting of
horizontal and vertical line segments in various positions with associated marker letters on a page. That night, the study
participants slept for various durations of time, where the amounts of SWS and REM sleep were recorded with the brain activity
monitor. Each day, for the next two days, the participants were tested on how well they could associate the images that they
studied on the first day with their respective marker letters. A control group of study participants that did not study the
first night also took the tests on the second and third days, in order to ensure the quality of the experiment.
One Block of Sleep:
Quality, not Quantity
The researchers
studied the results and observed that there was no improvement between the pre-test and the post-test among participants
who had slept less than 6 hours after the first training session. For participants who slept for more than 6 hours, the improvement
was proportional to both the amount of SWS sleep and also to the amount of REM sleep, which are maximized when the sleep stages
occur sequentially. In other words, in order to get adequate amounts of both SWS and REM sleep, the study suggests you must
sleep an uninterrupted sequential six+ hours. This implies that the common “Even though I only got four hours of sleep
last night, I’m gonna take a three hour nap in the afternoon and three plus four is seven, so I’m getting enough
sleep” is far less effective for long-term retention than the much less common “I’m gonna to get a more
than six hours of sleep tonight!”
Sleep Following Studying:
A One Shot Deal
Another interesting
finding was even though all of the participants had a full night’s rest the second night, those that didn’t get
over six hours of sleep the first night after studying did poorly on the retest on the third day, These results were very
similar to results of the first testing sessions. The researchers concluded that
both SWS and REM sleep after studying are absolutely necessary in “memory consolidation.” In other words, sleeping
a full night after learning is a one-shot, “do or die” deal.
As with all
science, this conclusion cannot be definitely proven, scientists can only show that strong evidence supports a conclusion.
This particular study has been reviewed by many cognitive neuroscience experts and has gotten a very positive response. It is also important to note that this study cannot be extrapolated to apply to higher
order thinking skills, just rote recall (which is nevertheless a highly valuable skill for tests!) So now the choice is yours:
stay up all night cramming for your midterm and then bomb your final, or ensure some “memory consolidation” by
getting a full night’s rest tonight!
Works Cited
Hohson, A., James, L., Stickgold,
R. 2000. Visual Discrimination Requires Sleep After
Training. Journal of Cognitive Neuroscience.
12: 246-254
Maquet, P. 2000. Sleep on it! Nature
Neuroscience 3: 1235-1236