Not getting enough sleep has a much greater effect on our ability to function the following day than previously believed, according to new research.
Past studies have shown that after a poor night’s sleep, our ability to pay attention becomes diminished, slowing our reaction time and impairing our ability to make decisions.
This new study, however, examined not only the effect of sleep deprivation on our ability to focus, but also on a higher-level cognitive function known as placekeeping, which is the ability to perform a set of steps or tasks in a particular order without making mistakes.
What the study found is quite troubling, given that a third of American adults report not getting enough sleep on a regular basis.
The research revealed that after a sleepless night, people are three times more likely to experience lapses in concentration and twice as likely to make placekeeping errors.
“Our findings debunk a common theory that suggests that attention is the only cognitive function affected by sleep deprivation,” said Michelle Stepan, the study’s lead author and a doctoral student at Michigan State University (MSU), in a released statement.
“Some sleep-deprived people might be able to hold it together under routine tasks, like a doctor taking a patient’s vitals,” she added. “But our results suggest that completing an activity that requires following multiple steps, such as a doctor completing a medical procedure, is much riskier under conditions of sleep deprivation.”
How the study was done
For the study, which was published in the Journal of Experimental Psychology: General, Stepan and her colleagues recruited 138 undergraduate students, aged 18 to 25, for an overnight sleep assessment. None of the students had been diagnosed with a memory or sleep problem, and none had a strong time-of-day preference. (In other words, none were overly “morning” or “evening” people.)
The participants were asked to sleep at least six hours on the night before the sleep assessment and to make sure they woke by 9 a.m. They were also instructed to refrain from napping that day and to forgo any caffeine, alcohol or drugs.
On the evening of the sleep assessment, the participants were brought to a research laboratory where they were given two separate cognitive tests. One measured how quickly they reacted to a stimulus. The other measured their placekeeping ability — how well they could follow a particular sequence of steps without omitting or repeating one of the steps, even with recurring interruptions.
After those tests were completed, 77 of the participants remained in the laboratory, where they were kept awake all night. The remaining 61 participants were sent home to sleep as they normally did.
The cognitive tests were repeated for both groups the following morning. The researchers then compared the two sets of tests, uncovering rather dramatic results.
“Our research showed that sleep deprivation doubles the odds of making placekeeping errors and triples the number of lapses in attention, which is startling,” said Kimberly Fenn, the study’s senior author and director of the MSU Sleep and Learning Lab, in a released statement.
On the placekeeping test, the error rate the night before the sleep assessment was 15 percent. That jumped to 30 percent the next morning for the students who were deprived of sleep. The error rate remained unchanged, however, for the students who went home and slept.
Time to take sleep seriously
This was a relatively small study, and involved only healthy, young undergraduate students, whose sleep requirements may differ from the general population. As the MSU researchers point out, college-aged students may need more sleep than older age groups and, therefore, may be more affected by a sleepless night.
Still, the findings are in line with plenty of other research on how sleep — or, rather, the lack of it — affects our critical thinking abilities.
The MSU researchers hope their results will help all of us recognize how a poor night’s sleep can hinder our ability to perform day-to-day tasks — and encourage us to take sleep deprivation seriously.
“Sleep-deprived individuals need to exercise caution in absolutely everything that they do, and simply can’t trust that they won’t make costly errors,” said Fenn. “Oftentimes — like when behind the wheel of a car — these errors can have tragic consequences.”
For more information: You can find an abstract of the study on the Journal of Experimental Psychology: General website, but the full study is behind a paywall.