Summary: A long-term Dutch study finds that people with an evening chronotype—commonly called night owls—tend to experience faster cognitive decline over ten years compared with morning types. The research links part of this increased risk to evening patterns of unhealthy behaviour, including poorer sleep, higher rates of smoking and alcohol use, and lower physical activity. Adjusting daily routines where possible and improving sleep quality may help reduce long-term brain health risks.
The study estimates that about 25% of the observed difference in cognitive decline can be explained by lifestyle factors such as smoking and poor sleep, particularly among highly educated people whose work schedules often force them to wake earlier than their natural rhythm. While chronotype is largely determined by biology and genetics, aligning work and sleep schedules with one’s internal clock can be a practical strategy to protect cognitive health as people age.
Key facts:
- Chronotype matters: Evening types showed greater decline in cognitive performance over a 10-year follow-up.
- Behavioural mediators: Smoking, worse sleep quality, and higher alcohol use explained a portion of the association.
- Practical takeaway: Forcing a schedule that conflicts with your chronotype—especially early start times—may accelerate cognitive decline; where possible, adapt work times or improve sleep habits.
Source: UMCG
Are you a morning person or an evening person?
According to research from the University Medical Center Groningen (UMCG) using large Lifelines cohort data, people who naturally stay up late and rise late show faster declines in certain cognitive abilities than those who are early risers. Ana Wenzler, a researcher involved in dementia prevention efforts, emphasises that behaviour change can partly mitigate this risk.
As populations age, preserving cognitive function becomes increasingly important. The BIRD-NL project, in which UMCG is a partner, investigates prevention strategies for dementia. Wenzler notes that brain function begins to change after age 40, and identifying modifiable lifestyle contributors is a central goal of this research.
What is your chronotype?
Chronotype refers to a person’s preferred timing of sleep and activity: are you naturally an early bird or a night owl? Wenzler studies sleep rhythms and how they relate to cognition. Using responses from the Munich ChronoType Questionnaire within the Lifelines dataset, researchers placed participants on a spectrum from extreme morning to extreme evening chronotypes.
The study tracked cognitive performance using standardized tests over a decade to compare baseline scores with results ten years later and determine whether chronotype predicted change in cognitive function.
More frequent unhealthy behaviour in the evening
The research found that evening chronotypes experienced greater declines in non-verbal fluency and executive function. One reason appears to be that unhealthy behaviours—more frequent smoking, greater alcohol consumption, poorer sleep quality, and lower exercise levels—were more common among evening types.
Overall, the investigators estimate that smoking and poor sleep quality together account for approximately 25% of the association between evening chronotype and cognitive decline. Notably, the effect was strongest among people with higher education, a subgroup that often faces early-morning work schedules that conflict with their natural sleep timing.
When early work start times force evening types to shorten sleep, the resulting sleep debt may leave the brain with inadequate rest and increase vulnerability to poor habits that further harm cognition.
Genetic patterns and life stages
Chronotype is influenced by genetics and changes across the lifespan. Children tend to be morning-oriented, then shift toward evening preferences during adolescence. For many people the tendency gradually returns toward morningness in their 20s and by middle age most are earlier types again, but not everyone follows this pattern—some individuals remain evening oriented into adulthood.
Because chronotype has a biological basis, changing it completely is difficult. Instead, researchers recommend adapting daily schedules and behaviours to fit one’s internal clock as much as possible.
Work against your body as little as possible
Wenzler cautions that forcing earlier sleep times won’t work if a person’s biology is not producing melatonin at that hour; the body simply resists. When evening people cannot align work schedules with their chronotype, they often get insufficient sleep and are more likely to develop unhealthy habits that compound cognitive risk.
Where feasible, employers and organisations could offer flexibility—such as later start times or staggered shifts—to accommodate evening chronotypes. Allowing people to follow a schedule closer to their biological clock could reduce sleep debt and lower the downstream risks associated with cognitive decline.
Follow-up research
Current follow-up studies led by Wenzler and colleagues are exploring whether evening chronotype is linked not only to faster midlife cognitive decline but also to a higher long-term risk of dementia. Faster decline in specific cognitive domains during middle age does not necessarily equate to greater dementia risk, so ongoing research aims to clarify the long-term implications and to develop tailored prevention advice.
About this chronotype and cognition research news
Author: Joost Wessels
Source: UMCG
Contact: Joost Wessels – UMCG
Image: The image is credited to Neuroscience News
Original research: Open access. “Chronotype as a potential risk factor for cognitive decline: The mediating role of sleep quality and health behaviours in a 10-year follow-up study” by Ana Wenzler et al., The Journal of Prevention of Alzheimer’s Disease. DOI reference included in the original publication.
Abstract
Chronotype as a potential risk factor for cognitive decline: The mediating role of sleep quality and health behaviours in a 10-year follow-up study
Background
With ageing populations worldwide, protecting cognitive health is a major public health priority. Chronotype—an individual’s preferred sleep–wake timing—may influence cognitive decline, potentially through intermediate factors such as sleep quality, alcohol intake, physical activity, and smoking.
Methods
Researchers analysed data from 23,798 participants aged 40 and over in the Lifelines cohort. Chronotype was measured using the Munich ChronoType Questionnaire and represented as a continuous score of corrected mid-point sleep. Multiple linear regression tested associations between chronotype and cognitive decline, with moderation tests for age, education, and sex. Mediation by sleep quality, alcohol consumption, physical activity, and smoking was assessed using the KHB method.
Outcomes
Cognition was measured with the Ruff Figural Fluency Test (RFFT), an assessment of non-verbal fluency and executive functioning. Cognitive decline was calculated by subtracting the baseline RFFT score from the 10-year follow-up score.
Results
Chronotype was associated with cognitive decline, and this relationship was moderated by educational attainment but not by age or sex. No significant association was found for low- or middle-educated groups. In the high-education group, each one-hour later chronotype corresponded to a 0.80-point greater decline on the RFFT per decade. In this subgroup, poorer sleep quality and current smoking mediated approximately 13.5% and 18.6% of the association, respectively.
Interpretation
Evening chronotype was linked to greater declines in non-verbal fluency and executive function among highly educated participants, suggesting the need for targeted prevention strategies that consider chronotype and related behaviours.
Funding
This work is part of the BIRD-NL consortium and was funded by the Dutch Medical Research Council (ZonMw) Dementia research programme.