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<\/a><\/p>\nSo when I hear about a study with over 10,000 participants, I sit up and take notice.<\/p>\n
In this case, researchers in Canada asked people to fill out online surveys about sleep, and to take cognitive tests<\/a>. Given their astonishing data pool, they can reach firm conclusions about the questions they’ve asked.<\/p>\n Some of these conclusions will sound quite predictable. Others will surprise you. They certainly surprised me.<\/p>\n First<\/strong>, if you want optimal cognitive function, roughly 7-8 hours <\/em>of sleep gives you the best results. (Assuming that “you” are an average person. Of course, not everyone is average.)<\/p>\n Second<\/strong>, that number doesn’t change with age<\/em>. (See below for an important caveat.) That is: 30-year-olds and 80-year-olds think best with the same amount of sleep.<\/p>\n Third<\/strong>, too much sleep<\/em> muddles cognition as much as too little sleep. As someone who likes sleeping, I’m sorry to say this but: the graphs don’t lie.<\/p>\n Fourth<\/strong>, non-optimal sleep\u00a0doesn’t harm short-term memory.\u00a0<\/em>Researchers tested short-term memory with the “spatial span task.” Participants had to remember which boxes flashed green, and press them in the same order. Here’s an example:<\/p>\n https:\/\/www.youtube.com\/watch?v=zWO_w3m4NQs<\/p>\n Instead, non-optimal sleep fuddles reasoning skills<\/em> (like executive function and deductive reasoning) and verbal skills<\/em> (like verbal working memory).<\/p>\n Of course, school requires A LOT of reasoning and verbal skill. No wonder sleep-deprived (or sleep-surfeited) students struggle.<\/p>\n (By the way,\u00a0fifth<\/strong>, 48.9% of the participants didn’t get enough sleep.)<\/p>\n And,\u00a0sixth,\u00a0<\/em><\/strong>a good night of sleep really does help. That is: people who got even one good night’s sleep before the test saw a measurable uptick in their cognitive performance.<\/p>\n From a researcher’s standpoint, it’s important to note that this team didn’t draw on a random sample. These participants volunteered by coming to a particular website<\/a>.<\/p>\n And, all of the data here come from self-report. People could be deceiving the researchers. They could also be deceiving themselves.<\/p>\n From a teacher’s standpoint, we should note the age cut-off<\/strong> for this study: 18 years. K-12 students might see similar patterns. That is: their short-term memory might be fine after low-sleep nights, while their reasoning and verbal skills suffer.<\/p>\n Or, entirely plausibly, younger people might see different effects. We just don’t know.<\/p>\n In my experience as a high-school teacher, my colleagues (and I) experienced sleep deprivation as much as our students did.<\/p>\nSleep and Cognition: Firm Conclusions<\/h2>\n
Caveats<\/h2>\n
A Final Note<\/h2>\n