Are you someone who stays up late and sleeps in, or do you prefer waking up early and starting your day at sunrise?
According to new research from the University Medical Center Groningen (UMCG) in the Netherlands, people who are “evening types”—those who go to bed and wake up late—may experience faster cognitive decline than morning people. The good news? Some of this decline can be slowed by changing daily habits.
Researcher Ana Wenzler, part of the BIRD-NL project focused on dementia prevention, led the study. She and her team used data from Lifelines, a large, long-term health research project in the Netherlands, to understand how sleep patterns relate to brain health.
Her main focus was on people’s chronotype—a biological term describing whether someone naturally functions better in the morning or the evening.
Chronotype is strongly influenced by biology. Most children start out as morning people, but during puberty, many shift to being night owls. By the time people reach their 20s, most begin to shift back toward being morning types.
By age 40, many have returned to preferring mornings—but not everyone. Evening types remain outside the norm, and Wenzler wanted to explore what this might mean for brain health.
In her research, Wenzler classified participants as morning people, evening people, or somewhere in between, based on when they reported going to bed and waking up. She then analyzed their performance on cognitive tests across a 10-year period. The findings were clear: people who preferred staying up late showed faster mental decline over time.
Why might this be the case? One explanation is that evening people tend to engage in more unhealthy behaviors, particularly in the late hours. Wenzler’s research found that evening types are more likely to smoke, drink alcohol, eat unhealthily, and exercise less.
Around 25% of the increased risk of cognitive decline in evening people could be explained by these habits, especially smoking and poor sleep quality.
Interestingly, the difference in cognitive decline was most noticeable in people with higher education levels. Wenzler suggests that this could be because they are more likely to have jobs with early start times, which force them to wake up earlier than their biological clock prefers. As a result, they may not get enough rest, which can harm the brain over time.
Wenzler points out that it’s difficult to change your chronotype. If your body doesn’t naturally produce the sleep hormone melatonin in the evening, trying to fall asleep early might not work.
Instead, she suggests adapting your schedule to fit your natural rhythm as much as possible—starting work later in the day, if your job allows it, or avoiding habits that can make things worse, like late-night smoking or drinking.
She also notes that people with less formal education may be more likely to have flexible or night-shift jobs that better match their chronotype. This may actually protect their brain health, compared to highly educated night owls forced into early routines that don’t match their internal clocks.
Wenzler and her team are now continuing their research to find out whether evening people are also more likely to develop dementia later in life.
While faster mental decline in middle age doesn’t always lead to dementia, the study could help clarify long-term risks. Ultimately, the goal is to give people practical advice for protecting their brain health over time—regardless of whether they’re early birds or night owls.
If you care about brain health, please read studies about how the Mediterranean diet could protect your brain health, and Omega-3 fats and carotenoid supplements could improve memory.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and higher magnesium intake could help benefit brain health.
The study is published in The Journal of Prevention of Alzheimer’s Disease.
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