Make no mistake: That midday slump is real. You’re not the only one who feels like curling up at their desk an hour or two after lunch. And while housing half a pizza at noon can weigh you down, food comas don’t explain the sluggishness. The culprit is our natural circadian rhythms, which dip in the afternoon. But there are ways to revive your facile mind before the day’s end. A recent study published in the journal PLOS ONE examined the cognition-boosting benefits of two decidedly different activities: napping and bright-light therapy.
One consequence of the afternoon slump is reduced cognitive flexibility, meaning sufferers become worse at alternating between different mental tasks. Task-switching, which falls under the executive-function umbrella, requires more cognitive control than repeated execution of the same drone-like function.
There’s evidence that naps and light-therapy sessions can facilitate cognitive recovery after skipping a night of sleep. Less research, however, has focused on using the techniques to combat losing steam after lunch. So, cognitive scientists took on the task.
For the study, 25 workaday warriors collectively participated in two separate experiments — one concerning naps and the other light therapy. For the three days leading up to the studies, participants wore sleep-monitoring wrist devices to ensure everyone got comparably solid rest.
Then, participants spent the equivalent of a workday in a lab. Everyone ate lunch — identical portions of lasagna — five hours after waking up. An hour after finishing lunch, half of the nap-experiment participants nodded off in a dark room for 30 minutes while the other half spent that time watching a documentary. All members of the light-therapy group watched the documentary; half of them wore a pair of light-emitting glasses and the other half wore a placebo device. Researchers administered tests to assess all participants’ cognitive flexibility at several points throughout the day.
Across the board, task-switching accuracy plummeted after lunch. People who subsequently took naps and did the real light therapy, however, showed improved performance on the final cognitive tests. Based on test results, control subjects (those who neither napped or soaked up real blue light) couldn’t shake off the cognitive fog. While both nappers and light-streamers showed sharper thinking skills than the fatigued control subjects, light therapy appeared to enhance both speed and accuracy more than napping.
These outcomes contrasted with earlier research on the cognitive benefits of napping versus light therapy, in which nappers emerged the victors. But the fact that light therapy edged out over napping may be the best outcome for workers because, well, it’s something that’s actually doable in a functioning office.
Still, the results may reflect certain details of the experiments. Previous studies, for example, involved sleep deprivation, whereas this study assessed the benefits of the two strategies on relatively well-rested people. Additionally, the napping conditions and duration may not have been ideal — researchers restricted rest to 30 minutes, assuming any longer might not be realistic during work.