A recent study has revealed new biological factors contributing to excessive daytime sleepiness (EDS), a condition that causes individuals to feel an overwhelming urge to sleep during the day, impacting their ability to function effectively. The findings, published on August 27, 2025, in The Lancet eMedicine, highlight the intricate relationship between genetic, biological, and lifestyle factors that influence alertness.
Research led by a team from Harvard-affiliated Beth Israel Deaconess Medical Center (BIDMC) and Brigham and Women’s Hospital utilized metabolite analysis to delve into the biological mechanisms behind EDS. The team aimed to uncover biomarkers that could provide a clearer understanding of why some individuals experience persistent sleepiness, even when their sleep habits seem adequate.
Tamar Sofer, co-corresponding author and director of Biostatistics and Bioinformatics at BIDMC, emphasized that while previous studies identified genetic variants linked to EDS, genetics alone do not account for the entire picture. “We wanted to identify biomarkers that can give stronger insights into the mechanisms of excessive daytime sleepiness,” she stated.
The investigation involved the analysis of blood samples from over 6,000 participants in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a comprehensive study funded by the National Institutes of Health since 2006. Researchers measured levels of 877 metabolites and compared these with participants’ self-reported sleepiness scores. They identified seven metabolites significantly associated with heightened levels of daytime sleepiness. Notably, these metabolites are involved in steroid production and other biological processes previously linked to EDS.
Further analysis revealed that among male participants, an additional three metabolites were identified, indicating potential sex-based differences in the manifestation of EDS.
The implications of these findings suggest that EDS may not merely stem from inadequate sleep but may also reflect underlying physiological conditions. This understanding could pave the way for blood tests to diagnose EDS and targeted interventions for treatment.
Lead author Tariq Faquih, a postdoctoral fellow in Sofer’s lab, remarked, “As we learn what’s happening biologically, we are beginning to understand how and why EDS occurs, the early signs that someone might have it, and what we can do to help patients.”
This research underscores the potential for new strategies in managing sleep disorders characterized by daytime sleepiness, a symptom that affects many individuals worldwide. The study was partially funded by the National Institute on Aging, highlighting the importance of continued research in this critical area of health.
With increasing awareness of EDS, the findings may lead to better diagnostic tools and interventions, ultimately improving the quality of life for those affected by this condition.
