Researchers at Imperial College London analyzed data from over 26,000 UK adults to explore how sleep duration, quality, and patterns influence cognitive abilities. The study, which employed data from the UK Biobank database, found that individuals who prefer evening activities — dubbed ‘night owls’ — generally score higher in cognitive tests compared to their ‘morning lark’ counterparts.

“Rather than just being personal preferences, these chronotypes could impact our cognitive function,” said lead author Dr. Raha West, from Imperial’s Department of Surgery and Cancer.

The Impact of Sleep on Cognitive Performance

The study determined that sleeping seven to nine hours each night optimizes brain function, enhancing memory, reasoning, and information processing speed. Conversely, sleeping less than seven hours or more than nine hours adversely affects cognitive performance.

That’s in general — getting enough quality sleep will make your brain operate better no matter your bedtime routine. However, all things being equal, the researchers found a significant cognitive performance gap between chronotypes.

A person’s chronotype refers to the inclination towards morning or evening activities. Night owls consistently scored better than morning larks. In one group, evening types scored 13.5% higher, and in another, they scored 7.5% higher than morning types. Intermediate sleepers — those without a strong preference — also performed better, scoring between 6.3% and 10.6% higher than morning types.

These differences remained significant even after adjusting for factors such as age, gender, smoking, alcohol consumption, and chronic diseases. Younger, healthier individuals generally performed better on cognitive tests, as expected.

Dr. West emphasized, “It’s important to note that this doesn’t mean all morning people have worse cognitive performance. The findings reflect an overall trend where evening types might lean towards better cognition.”

What This Data Means for Us

The study suggests that working with natural sleep tendencies is optimal for cognitive health. Adjusting sleep habits, such as modifying bedtime, increasing evening light exposure, and maintaining a consistent sleep schedule, can enhance cognitive function. However, completely switching from a morning to an evening chronotype is challenging. This is why the recommendation is for people to clock in their optimal bedtime hours. One shouldn’t fret too much about being a morning or evening person. Previous research showed that such traits are heritable.

“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. We’d ideally like to see policy interventions to help sleep patterns improve in the general population,” said co-author Professor Daqing Ma.

While the study highlights the importance of sleep duration, it also surprisingly found that insomnia did not significantly lower cognitive performance, suggesting the need for further research into insomnia’s specific aspects.

“We’d ideally like to see policy interventions to help sleep patterns improve in the general population,” said study co-author Professor Daqing Ma, also at Imperial’s Department of Surgery and Cancer.

The findings appeared in the journal BMJ Public Health.