Chronotype and synchrony effects in human cognitive performance: A systematic review.
Level 3 - non-randomized controlled study
Systematic review of predominantly observational and quasi-experimental human performance studies.
PubMed 40293205 · doi:10.1080/07420528.2025.2490495
What was done
Following PRISMA guidelines, the authors searched PubMed and Web of Science through March 11, 2024, to evaluate how chronotype alone or interacting with time of day (optimal vs. non-optimal, termed the synchrony effect) influences cognitive function in healthy adults. The review identified 65 studies: 53 in adults aged 18–45 years, 11 comparing adults aged 18–32 and 50–95 years, and 1 in morning-type adults aged 60–76 years.
What was found
More than 80% of reviewed studies found no main effect of chronotype alone on cognitive function. Evidence of a synchrony effect (better performance at optimal time of day) was present in 29 of 64 studies (45.31%) in younger adults (aged 18–45), mainly in attention, inhibition, and memory tasks. In older adults, 10 of 12 studies (83.33%) found a synchrony effect, especially on fluid ability tasks. Limited evidence showed higher activation in inhibition-related brain regions at optimal times of day.
Why it matters
Cognitive assessments that do not account for chronotype and testing time may mischaracterize individual performance, potentially exaggerating measured cognitive deficits in older adults.
Limits
The abstract does not report pooled effect sizes or the total number of individual participants across the 65 studies. Synchrony effects were inconsistent in younger adults (observed in fewer than half of studies), and data on brain activation and exogenous moderators (such as lighting and task complexity) were limited.
Cited by
- supports A person's ability to understand complicated concepts improves when they are more in line with their chronotype.