NEW YORK, May 29: Individuals who regularly stay up late and go to bed late—commonly known as night owls—are more likely to experience faster cognitive decline than early risers, according to new research from the University Medical Center Groningen (UMCG).

The study, conducted by researcher Ana Wenzler, is part of the national BIRD-NL project, which explores strategies to prevent dementia as the population ages. Wenzler emphasizes that while biological predispositions play a role, some risks can be reduced through behavior changes.

“The good news is that this decline can be partly influenced by behavior,” said Wenzler, who focuses her research on dementia prevention. “After the age of 40, the brain naturally begins to deteriorate. Our goal is to identify lifestyle or environmental factors that can lower the risk.”

Wenzler’s study examines the concept of chronotype, which refers to a person’s natural tendency to be active at certain times of day. Using data from the long-term Lifelines health study, researchers analyzed participants’ sleep patterns and classified them from early risers to night owls based on self-reported sleep habits. The team then tracked changes in cognitive function over a 10-year period by comparing test scores from the beginning and end of the study.

The results revealed that night owls were more likely to experience a sharper decline in cognitive abilities. Wenzler noted that this group tends to engage more frequently in unhealthy behaviors such as smoking, drinking, poor diet, and lack of exercise—especially during evening hours. “About 25% of the cognitive decline we observed can be attributed to smoking and poor sleep,” she said.

Interestingly, the findings were most pronounced among highly educated individuals, likely due to job constraints that force early waking despite a late chronotype. “This mismatch can lead to insufficient sleep, depriving the brain of necessary rest,” Wenzler explained.

She also noted the natural shifts in chronotype over a lifetime. While most people begin as morning types in childhood, many shift toward evening habits during adolescence and gradually revert to morning tendencies by their 40s. However, some adults remain night owls, which places them outside the biological norm.

Wenzler advises individuals to avoid working against their body’s natural clock whenever possible. “Going to bed earlier doesn’t help if your body hasn’t begun producing melatonin. It simply won’t be ready to sleep,” she said.

She pointed out that some jobs, particularly in hospitality or shift work, may offer more flexibility for evening types, allowing better alignment with natural sleep rhythms. “Without that flexibility, the brain suffers from a lack of rest, increasing the likelihood of unhealthy behaviors. Offering later start times could significantly benefit night owls,” she suggested.

The UMCG team is now investigating whether night owls also face a higher risk of developing dementia later in life. “While faster cognitive decline in midlife doesn’t necessarily lead to dementia, we want to understand the long-term implications better,” Wenzler said. “Ultimately, our research aims to offer practical advice to help people reduce their dementia risk.”