Summary: New research finds that, after accounting for factors like bedtime and age, people who prefer mornings tend to show stronger verbal abilities than night owls, challenging earlier reports.
Source: University of Ottawa
Night owls may welcome the return to standard time this autumn, but a recent study from the University of Ottawa suggests that Daylight Saving Time is not necessarily at odds with the strengths of morning people.
Led by Dr. Stuart Fogel, a cognitive neuroscientist and professor in the School of Psychology at the University of Ottawa, the study explores how an individual’s daily rhythm—known as chronotype—and patterns of activity during wake and sleep relate to measures of human intelligence. While prior research sometimes indicated evening types, or “owls,” had an edge in verbal intelligence, Fogel’s team reports a more nuanced result: when controlling for critical variables such as bedtime and age, morning types showed superior verbal ability.
“Once you account for key factors including bedtime and age, we found the opposite to what earlier work suggested — morning types tend to have better verbal skills,” says Stuart Fogel, Director of the University of Ottawa Sleep Research Laboratory. “This was surprising and shows the relationship between circadian rhythm and cognition is more complex than previously understood.”
The researchers identified each volunteer’s chronotype—whether they are naturally inclined to be active in the morning or evening—by combining self-report measures with objective monitoring of biological rhythms. Chronotype reflects when during the day a person is most alert and able to perform demanding tasks, from learning and problem solving to physical exercise.
Chronotype also varies with age: younger people, including many adolescents, are more likely to be evening types, while older adults generally shift toward morningness. The team highlights an important social implication: many school and work schedules are set to match typical morning routines, which can put evening-type students at a disadvantage by forcing them to perform cognitively demanding tasks at times that conflict with their internal clocks.
“A lot of school start times are not aligned with children’s natural chronotypes but are driven by parents’ and workplaces’ schedules. As a result, school-aged children who are evening types are often required to follow a morning timetable that doesn’t match their peak performance times,” Fogel explains.
For example, subjects such as math and science are often scheduled early in the day under the assumption that morning times suit cognitive work. However, if a student is an evening type, the early schedule may suppress their ability to perform at their best, effectively forcing them to fight their biological clock every school day.
The study recruited participants across a wide age range and carefully screened them to exclude sleep disorders and other confounding conditions. Participants completed established questionnaires about morningness and eveningness and wore activity monitors—actigraphy devices—for ten days. These objective measurements captured bedtimes, rise times, total sleep duration, and the regularity and amplitude of daily activity rhythms.
Key to interpreting the results was the strength of an individual’s circadian rhythm—how consistently their activity patterns repeated day to day. The researchers combined actigraphy data with cognitive testing that measured verbal ability, reasoning, and short-term memory to examine how chronotype and rhythm stability relate to trait-like cognitive abilities.
“Our brains function best with regularity. Maintaining consistent sleep-wake patterns supports stronger circadian synchronization, which in turn appears linked with cognitive performance,” Fogel says. Age and actual sleep timing emerged as important contributors to these associations.
About this circadian rhythm and verbal intelligence research news
Author: Paul Logothetis
Source: University of Ottawa
Contact: Paul Logothetis – University of Ottawa
Image: The image is in the public domain
Original Research: Open access. “Does the early bird really get the worm? How chronotype relates to human intelligence” by Stuart Fogel et al., Current Research in Behavioral Sciences. DOI: 10.1016/j.crbeha.2022.100083
Abstract
Does the early bird really get the worm? How chronotype relates to human intelligence
Objectives
Chronotype affects how we feel and perform at particular times of day. It is also a heritable, trait-like characteristic that changes with age and differs by sex. Despite its potential importance, evidence linking chronotype to stable cognitive abilities, such as intelligence, has been limited and inconsistent. Past studies often relied on subjective chronotype measures, focused mainly on young adults, and overlooked sex differences. This study combined aptitude testing, subjective chronotype assessment, and objective actigraphy to clarify the relationship between chronotype and trait-like cognitive abilities.
Design
Sixty-one participants (44 female; mean age 35.30 ± 18.04 years) completed the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) to report their subjective chronotype. They also wore an activity monitor for ten days to capture bedtime, wake time, total sleep time, inter-daily stability, intra-daily variability, and relative amplitude—measures that quantify the strength and regularity of circadian rhythms. After monitoring, participants completed cognitive tests assessing verbal ability, reasoning, and short-term memory.
Results
Higher MEQ scores (indicating greater morningness) correlated with stronger inter-daily stability, meaning more consistent daily rhythms. The analysis showed superior verbal ability was linked to later bedtimes and younger age, but, paradoxically, also to higher (more morning) MEQ scores once evening-type behaviors were accounted for. Short-term memory performance was primarily associated with younger age. These relationships were similar across sexes and did not differ significantly between younger and older adult groups.
Conclusions
This study demonstrates that the MEQ measure of chronotype strongly relates to the stability of daily rhythms. While evening types may show stronger verbal skills in some analyses, when controlling for behaviors associated with being an evening type—such as later bedtimes—greater morningness as measured by the MEQ was associated with superior verbal abilities. Overall, the findings emphasize the complex interplay between chronotype, sleep timing, rhythm regularity, and cognitive performance, with implications for education, work scheduling, and public health.