‘Night owls’ are mentally sharper than ‘morning larks’ 

A study examining the impact of sleep on brain function discovered a link between an individual’s preference for morning or evening activity and their cognitive performance, suggesting that “night owls” generally score higher cognitively.

Researchers from Imperial College London (ICL) analyzed data from over 26,000 people to investigate how various aspects of sleep – such as duration, patterns, and quality – affect mental sharpness and cognitive ability. 

Using data from the UK Biobank, they examined whether participants identified as “morning people” or “evening people,” indicating their most alert and productive times of the day.

The mysterious function of sleep 

“Sleep is a fundamental biological behavior that is universally conserved throughout evolution. However, despite its significance, the function of such a process remains a long-debated subject of interest,” wrote the study authors. 

“Emerging studies suggest that sleep plays a crucial role in optimizing cognitive function by contributing to bodily restoration, memory consolidation, learning and emotional regulation. Sleep impairment, particularly common among elderly people, has been consistently linked to an increased risk of cognitive decline and dementia.” 

“Homeostatic immune function is also profoundly influenced by sleep, and sleep impairment has been linked to immune-related neurodegenerative, metabolic, autoimmune and vascular diseases.”

“Animal studies have further shown that, mechanistically, sleep disturbance induces neuroinflammation, complement activation, impaired learning and memory, and affects hippocampus-dependent learning.”

Sleep duration and cognitive performance

The researchers noted that population-based studies have highlighted the relationship between sleep duration and cognitive abilities, indicating potential cognitive impairments associated with both short and long sleep durations.

Published in BMJ Public Health, the study revealed that sleeping between seven to nine hours per night optimizes brain function, enhancing cognitive abilities such as memory, reasoning, and information processing speed. 

In contrast, sleeping for fewer than seven hours or more than nine hours had a negative impact on cognitive function.

Night owls outperformed morning larks

The study also highlighted the influence of a person’s chronotype, which refers to their preference for morning or evening activity. “Night owls” – those who are naturally more active in the evening – outperformed “morning larks” in cognitive tests. 

Larks consistently scored the lowest, with intermediate types – those with a mild preference for either day or night – performing better, and evening types achieving the highest scores.

Night owls scored approximately 13.5% higher than morning larks in one group and 7.5% higher in another group. 

Intermediate sleepers scored around 10.6% and 6.3% higher than morning types in the two groups, respectively. These differences were statistically significant, indicating they are unlikely to be due to chance.

Night owls’ cognitive performance

The analysis accounted for various health and lifestyle factors, including age, gender, smoking, alcohol consumption, and chronic diseases like heart disease and diabetes. 

Generally, younger individuals and those without chronic conditions scored higher in cognitive tests, while healthier lifestyle choices were linked to better cognitive performance.

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

However, West emphasized that the findings do not imply all morning people have poorer cognitive performance, but rather that the overall trend favors evening types. 

Proactively managing sleep patterns 

West noted that shifting natural sleep habits is complex, but understanding and working with one’s sleep tendencies while ensuring sufficient sleep duration is crucial for brain health.

Interestingly, while sleep duration was critical, people with insomnia did not score significantly lower in cognitive performance. This suggests that specific aspects of insomnia, such as severity and duration, need to be considered.

“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 co-lead author Daqing Ma.

“We’d ideally like to see policy interventions to help sleep patterns improve in the general population.”

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