Those who don’t sleep well are usually not at the forefront of their minds the next day. As a new study shows, one aspect in particular affects our cognitive fitness.
- In the video above: What happens to your psyche if you don’t sleep until after midnight
Restless nights with periods of wakefulness in between appear to have a significantly greater impact on mental abilities the next day in older adults than, for example, shorter sleep durations. That’s the finding of a new study by a team of researchers from Pennsylvania University and the Albert Einstein College of Medicine in New York.
“Anyone who has ever stayed up too late knows that sleep can impair cognitive abilities the next day,” says behavioral biologist and lead author Orfeu Buxton. “In this study, we wanted to find out which aspects of sleep health impact daytime cognitive function so people know how to improve their sleep.”
Researchers are studying how sleep affects cognitive function
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In one experiment, those participants who had longer periods of wakefulness than usual the previous night performed significantly worse on short thinking tasks, as the group reports in the specialist journal “Sleep Health”. On average, the participants slept 7.2 hours per night and spent a good hour awake.
“Waking up repeatedly after falling asleep worsens the overall quality of your sleep,” explains Buxton. “We examined various aspects of sleep, and sleep quality is the only factor that affects cognitive performance on a daily basis.”
Interrupted sleep makes the brain slow the following day
For the study, 261 subjects over the age of 70 in New York wore digital bracelets, similar to smartwatches, that tracked their sleep and wakefulness phases for 16 days. In addition, they were given small, playful brain teasers on their smartphones six times a day, each lasting around four minutes and targeting various mental abilities – such as visual working memory, spatial memory or the speed of processing information.
Those participants who were awake for more than 30 minutes longer than usual the previous night showed a significantly slower processing speed of information. Surprisingly, both sleep duration and naps the day before had no such measurable effect as sleep quality.
Improving sleep quality can delay dementia
The team compared the results of the seniors not only in terms of better and worse nights for each test subject, but also in terms of differences between different people.
It turned out that those who generally slept worse, i.e. who spent more time awake at night, performed worse in three out of four cognitive tests – in addition to the tasks involving information processing, they also performed worse in two tasks that required visual working memory.
Co-author and neurologist Carol Derby emphasized that the findings could provide information about which people have an increased risk of dementia, for example. Over long periods of time, sleep problems can be linked to reduced mental abilities and the development of dementia diseases such as Alzheimer’s, according to the authors. Improving sleep quality can therefore delay dementia, says Derby.
How to sleep better
But this is often easier said than done for those affected. How can sleep quality be improved? The study authors have a few recommendations: If possible, you should go to sleep at the same time in a quiet, dark environment and avoid screen time right before you fall asleep.
If sleep problems persist, cognitive behavioral therapy can help. However, the researchers advise against medication. And Buxton has another very simple piece of advice: “My most important advice is not to worry about sleep problems. Worrying only causes stress, which can further disrupt sleep.”
