Study Finds Sleep Quality Is a Key Predictor of Cognitive Task Performance in Students
Sleep is often overlooked in academic life, yet it plays a central role in how students think, learn, and solve problems. A new peer-reviewed study explores how sleep quality affects cognitive performance in university students from Tokyo and London. Published in Frontiers in Sleep in May 2025, the research reveals cross-cultural differences in sleep habits and mental function. Here’s what the authors found.
Note: This article is intended for general information and educational purposes. It summarizes scientific research in accessible language for a broad audience and is not an official scientific press release.
Researchers from Waseda University in Tokyo and King’s College London collaborated on a study published in May 2025 in the journal Frontiers in Sleep. The authors investigated how sleep quality relates to cognitive performance in university students across two different cultures: Japan and the UK. Using both subjective and objective measures of sleep along with standardized cognitive tasks, the study examined whether sleep quality might influence mental functioning and whether this effect differs by location.
What the Researchers Investigated
The study aimed to explore the relationship between sleep quality and cognitive performance in students and whether this relationship varies across cultural contexts. The research team, led by Dr. Ayaka Takahashi and Dr. Simon Bell, recruited university students from Tokyo and London. The study used both subjective reports (via the Pittsburgh Sleep Quality Index, PSQI) and objective actigraphy-based measures of sleep, alongside a battery of cognitive tests.
Participants included 200 university students —100 from each city. All were healthy, full-time students with no diagnosed sleep or psychiatric disorders. Sleep quality was assessed using the PSQI, and participants wore actigraphy devices to measure real-time sleep duration and efficiency. Cognitive tasks included the Rey Auditory Verbal Learning Test (RAVLT), Stroop Test, Raven’s Progressive Matrices (RPM), and the Wisconsin Card Sorting Test (WCST).
How the Study Was Conducted
The study followed a cross-sectional design. Participants completed sleep quality questionnaires and wore actigraphy devices for seven nights. Cognitive performance was evaluated using validated tasks that measure verbal memory, attention, reasoning, and cognitive flexibility.
The PSQI assessed subjective sleep quality across seven components including latency, duration, and disturbances. Actigraphy provided objective data on total sleep time and sleep efficiency. The cognitive tasks measured multiple mental abilities: RAVLT (verbal learning and memory), Stroop (inhibitory control), RPM (nonverbal reasoning), and WCST (executive function).
The analysis included correlation tests and regression models to determine whether sleep quality was associated with performance, and whether the results differed between the two cultural groups. The authors also conducted moderation analyses to investigate whether location influenced the strength of the relationship between sleep quality and mental performance.
What Makes This Study New
According to the authors, the cross-cultural design is a distinguishing feature of this research. The study directly compared two culturally and geographically distinct populations using identical procedures and tools. The authors highlight that this approach allows for a more nuanced understanding of how cultural norms may influence both sleep behavior and its cognitive correlates.
The authors also emphasize the integration of both subjective and objective sleep metrics as a methodological strength. This allowed them to investigate whether perceptions of sleep align with physiological data and how each relates to mental performance.
Additionally, the use of well-established, performance-based cognitive tasks provides an important contribution to the field. The authors note that many previous studies have focused on self-reported outcomes or academic performance, whereas their research directly assesses cognitive function using standardized neuropsychological tests.
Key Findings from the Study
According to the authors, students in Tokyo reported significantly poorer sleep quality than those in London (Mean PSQI = 9.2 vs. 7.8; p < 0.001).
Objective actigraphy data indicated that Tokyo students had shorter sleep duration (6.1 h vs. 6.9 h; p < 0.001) and lower sleep efficiency (82.5% vs. 87.5%; p < 0.01).
London students performed better than their Tokyo counterparts on all four cognitive assessments, including tasks involving verbal memory, reasoning, attention, and flexibility (all ps < 0.01).
The authors reported significant negative correlations between PSQI scores and cognitive performance. Higher PSQI scores, indicating poorer sleep quality, were associated with lower scores on all cognitive tasks.
Regression analyses showed that PSQI scores remained a significant predictor of cognitive performance even after adjusting for age, gender, and actigraphy data.
Moderation analysis indicated that the link between poor sleep quality and lower verbal memory performance was stronger among Tokyo students compared to London students.
Authors’ Conclusions
The authors conclude that sleep quality is closely linked to cognitive functioning and that this relationship may vary by cultural context. They suggest that differences in academic expectations, societal norms, or urban lifestyle may contribute to the observed disparities between Tokyo and London students.
The study also notes that subjective sleep quality appears to be a reliable predictor of cognitive performance, independent of objective measures. The authors suggest that how people perceive their own sleep may have real consequences for mental function.
They acknowledge some limitations, including the cross-sectional design, which does not allow for causal inferences. They also highlight the need for future research to explore underlying mechanisms and examine whether interventions aimed at improving sleep might enhance academic performance.
Finally, the researchers propose that incorporating sleep education and awareness into student support programs could be valuable. Although their study does not test interventions directly, the consistent link between sleep and mental function points to an area worth exploring in future work. They emphasize that further studies, particularly those using longitudinal or interventional designs, are needed to fully understand these complex interactions.
You can read the original study here: https://doi.org/10.3389/frsle.2025.1537997
The information in this article is provided for informational purposes only and is not medical advice. For medical advice, please consult your doctor.
