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September 29, 2023 TORONTO, September 26, 2023 – Whether you are an early bird or a night owl, your internal clock plays a critical role in maximizing your mental performance, according to a recent Baycrest study. This effect is so strong that it can significantly impact academic performance for adolescent students and the results of brain health assessments for older adults.

“A person’s tendency to be a morning or an evening person is called their chronotype. Because of differences in chronotypes, we see significant differences in the time of day at which people are best at paying attention, learning, solving problems, making complex decisions and more," says Dr. Lynn Hasher, Senior Scientist at Baycrest’s Rotman Research Institute, the study's lead author and a key leader in this field of research.

An individual’s chronotype drives physiological and intellectual functioning throughout the day. Morning chronotypes rise and peak early in the day, while evening chronotypes have a later peak. Chronotype varies from person to person and also changes with age, from childhood to adolescence to old age. In general, adolescents are likely to be night owls, while older adults are more likely to be morning people.

In this scientific literature review, the researchers analyzed more than 150 previously published studies examining chronotypes and their effects on mental performance. Conducting the research with Dr. Hasher were Dr. Cynthia May (Professor of Psychology, College of Charleston) and Dr. Karl Healey (Associate Professor of Psychology, University of Michigan).

They found that a person’s chronotype has a strong effect on their ability to pay attention, learn, solve problems, make complex decisions and even behave in an ethical manner. This means that a morning person may have more difficulty learning new information later in the day, while an evening person may struggle to make decisions before noon.

Chronotype appears to have the strongest impact for adolescents and older adults. Adolescents are generally strong evening chronotypes, but they tend to start school early in the morning, which may have a negative effect on their academic performance. In addition, because the majority of older adults show a strong biological preference for the morning, they tend to perform much worse on cognitive tests later in the day, which could in turn lead to unnecessary stress.

Overall, these results indicate the importance of recognizing and accounting for chronotype in a wide variety of settings, from academic and medical situations to social settings and more.
"By better understanding and acknowledging chronotypes, we can help individuals optimize their mental performance and live their best possible lives, no matter their age,” says Dr. Hasher.
This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the National Science Foundation and the National Institute on Aging.

About Baycrest
Baycrest is a global leader in aging and brain health with a vision of a world where, with your help, we can all Fear No AgeTM.  Baycrest provides everyone the tools they need to make their later years the best years of their lives. Through our work in research, innovation, care and education, we are working to defeat dementia and create a world where every older adult enjoys a life of purpose, inspiration and fulfilment. For more information about Baycrest, visit
About Baycrest’s Rotman Research Institute
The Rotman Research Institute at Baycrest is a preeminent international centre for the study of aging and human brain function. Through generous support from private donors and funding agencies, the RRI advances our understanding of human brain structure and function in critical areas of clinical, cognitive, and computational neuroscience, including perception, memory, language, attention and decision making. With a primary focus on aging and brain health, including Alzheimer’s and related dementias, research at the RRI and across the Baycrest campus promotes effective care and improved quality of life for older adults through research into age- and disease-related behavioural and neural changes.
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