Sleep is thought to play a critical role in memory. The links aren’t fully understood but it’s clear that someone who hasn’t slept well won’t function as well at work or school. Sleep also seems to play a role in helping us consolidate learning done during the day; cementing memories in our brain while we’re unconscious so we can recall them later.
Part of the reason why we don’t know more is that sleep is difficult to study. Short of bringing someone into a sleep lab and observing them (which is time-consuming and expensive), you have to rely on what people tell you about their sleep, which isn’t always reliable. That’s changing though, with the development of Fitbit-like devices worn during slumber that can provide all sorts of information about sleep.
In new research using this measure of sleep quality, researchers gave about a hundred university students Fitbits to wear during the semester.
The original aim of the study was to see how exercise and activity influenced their exam success but when the researchers found no link between the two, they decided to re-examine the data to see if more clues could be found in the sleep information. They had data on when each student went to sleep, how long they slept for, the quality of their sleep (how often they woke up or were restless in the night) and when they woke up.
There were a few obvious findings such as getting higher quality sleep, and more sleep, being linked to higher grades. But they also found that consistency was key; someone who slept for a shorter amount of time but who went to bed and woke up at similar times during the week, seemed to do better than someone who got a good amount of sleep but had varied sleep and wake times.
It wasn’t enough to get a good sleep on the night before an exam. Again, consistency was key and someone’s sleep over a week or month-long period was a better predictor of their exam success than just the previous evening. When someone slept didn’t seem to matter much to their grades. They did well whether it was 9pm or midnight, except if someone stayed up past 2am. Even if they got a good amount of sleep, their performance seemed to be affected.
It’s a small sample size and a young group of people but the lesson here seems to be that consistency is important along with sleep quality as opposed to how many hours sleep they had, which is consistent with previous research.