'Night owls' traditionally get a bit of a rough time of it, with numerous studies linking staying up late to poor health outcomes, inadequate sleep and a fair amount of shame that comes with not being able to function as well in the mornings as others. And, in a world where work hours generally favor early risers, the late-night folk can feel a little out of step with society.
But there's finally some good news for those who can't, or don't want to, go to bed at a 'reasonable hour,' with Imperial College London (ICL) scientists finding that night owls have significantly greater brain function than their early-rising counterparts. So, if you're in that camp of believing the day doesn't truly start until 5pm, this one is for you.
“Our study found that adults who are naturally more active in the evening (what we called 'eveningness') tended to perform better on cognitive tests than those who are 'morning people,'" said the study's lead author Raha West, from the Department of Surgery and Cancer at ICL. "Rather than just being personal preferences, these chronotypes could impact our cognitive function."
Previous studies have associated 'eveningness' to detrimental health outcomes, including putting them at greater risk of type 2 diabetes and heart disease, and even a 10% higher risk of early death compared to 'morning people.' Night owls have also been linked to having a higher rate of psychological and neurological disorders.
Genetics studies have indicated that morning-night sleep preferences is closely tied to our biology, with variants associated with a shift in circadian rhythms that play a big role in when we feel we need to sleep. This is, of course, still very much a work in progress, but we do know that night-owl behavior is complex and not just governed by personal choice or willpower.
Recently, it's even been tied to evolution, linking attention-deficit/hyperactivity disorder (ADHD) and 'eveningness' with something deemed the Watchman Theory. It suggests that for the nearly three quarters of ADHD sufferers who report sleep problems, including "bedtime resistance," it might be traced back to hunter-gatherer days, when those genes and time-shifted circadian rhythms made a certain group of people excellent at keeping watch over tribes late into the night.
Whatever the driver, being a night owl might come with some benefits after all. In this latest study, researchers looked at more than 26,000 UK Biobank participants and their sleep habits – including duration and quality – and how they performed on cognitive tests. These participants also self-described themselves as morning or night people.
After adjusting for health and lifestyle factors, such as chronic disease, smoking and alcohol intake, the researchers found that night owls scored around 13.5% higher than morning people in one group, and 7.5% higher in another group. What's more, morning people had consistently lower test scores across the board, with even the 'intermediate' types – those who considered themselves more somewhere in the middle – doing 10.6% and 6.3% better than early risers.
“It's important to note that this doesn't mean all morning people have worse cognitive performance," said West. "The findings reflect an overall trend where the majority might lean towards better cognition in the evening types. While it’s possible to shift your natural sleep habits by gradually adjusting your bedtime, increasing evening light exposure, and keeping a consistent sleep schedule, completely changing from a morning to an evening person is complex.”
But key to the findings also appears to be the amount of sleep per night – which is probably not such a surprise. In their findings, the researchers noted that between seven and nine hours of shut-eye is best for our brains, particularly in connection with memory and information processing speed. However, they also found that getting more than nine hours was actually linked to poorer brain function.
And in another surprising outcome of the study, those who reported suffering from insomnia didn't show a significant drop in brain function as a result of poor sleep. But the scientists said this was likely more nuanced, with the findings not factoring in the duration or severity of insomnia.
“While understanding and working with your natural sleep tendencies is essential, it's equally important to remember to get just enough sleep, not too long or too short," said West. "This is crucial for keeping your brain healthy and functioning at its best.”
So, what does this mean for night owls? Staying up late may be better for brain performance than rising early – as long as you're able to hit the sweet spot of seven to nine hours of sleep. Which, of course, can be challenging with external factors such as work and family commitments.
Previous research has also looked at interventions such as strobe-light therapy to help night owls get better-quality and enduring sleep, to help with daytime function.
“We’ve found that sleep duration has a direct effect on brain function, and we believe that proactively managing sleep patterns is really important for boosting, and safeguarding, the way our brains work," said study co-leader Daqing Ma, a professor in ICL's Department of Surgery and Cancer. "We’d ideally like to see policy interventions to help sleep patterns improve in the general population.”
The study was published in the journal BMJ Public Health.
Source: ICL
