Seven blood metabolites tied to excessive daytime sleepiness; omega‑3 and omega‑6 linked to lower risk
Analysis of 6,000 participants finds dietary fatty acids associated with reduced daytime drowsiness while tyramine and sex‑specific molecules correlate with higher sleepiness
Researchers have identified seven blood metabolites associated with excessive daytime sleepiness (EDS), a finding that highlights potential biological and dietary contributors to persistent daytime drowsiness and suggests targets for future intervention studies.
The study, led by sleep researchers at Brigham and Women's Hospital and published in eBioMedicine, analysed 877 naturally occurring molecules in the blood of roughly 6,000 participants from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Seven metabolites stood out for their association with self‑reported daytime sleepiness, with omega‑3 and omega‑6 fatty acids linked to a lower risk and the amino compound tyramine associated with increased sleepiness and poorer nighttime sleep, particularly in men.
Investigators used metabolomic profiling, which measures small molecules influenced by diet, hormones and environment, and correlated those measures with survey responses about the frequency of dozing off in everyday situations. The analysis identified several molecules related to lipid metabolism—most notably unsaturated fatty acids typically found in fatty fish, egg yolks and nuts—that were associated with reduced odds of reporting daytime drowsiness.
"Our study suggests diet and genetics may play an important role in EDS," said Dr. Tariq Faquih of Brigham and Women's Hospital. "As we learn what's happening biologically, we are beginning to understand why EDS occurs, the early signs that someone might have it, and what we can do to help patients."
Tyramine, a compound found in fermented and overripe foods, showed the opposite pattern: higher blood levels were linked to an increased risk of EDS and to delayed or poorer sleep quality at night. The team also identified three additional metabolites whose associations with sleepiness differed by sex; the analysis pointed to hormone‑related pathways, including links between progesterone and processes involved in melatonin production.
Excessive daytime sleepiness affects a substantial portion of the population—estimates cited by the authors and media reports put prevalence at up to one‑third of U.S. adults—and is associated with higher risks of obesity, diabetes and cardiovascular disease. The researchers say their findings emphasize the interplay of diet, hormones and genetics in sleep regulation and could inform preventive or therapeutic strategies.
The study has limitations that temper its conclusions. Sleepiness and sleep quality were measured by questionnaire rather than laboratory‑based sleep studies, which can be more precise. The authors also noted challenges in translating single blood metabolite measurements into definitive biological effects and cautioned that observational associations do not establish causation.
Because the results are observational, the authors called for clinical trials to test whether increasing dietary omega‑3 and omega‑6 intake can reduce the risk of EDS. "Conducting a clinical trial would be a big next step and could help us understand if omega‑3s and omega‑6s obtained from diet could help lower risk of EDS," Dr. Faquih said.
The findings align with other research linking unsaturated fatty acids to brain and metabolic health. Separately, British researchers have reported that women with Alzheimer's disease had lower levels of certain healthy unsaturated fats in their blood, a result that investigators say could help explain sex differences in disease prevalence and open avenues for prevention research.
The Brigham team and other sleep scientists say further work is needed to replicate the metabolite associations in diverse populations, to use objective sleep measures such as polysomnography or actigraphy, and to determine whether dietary or supplement interventions can alter metabolite levels and improve daytime alertness. Until then, clinicians may consider diet and hormonal status among multiple factors when assessing patients who report persistent daytime sleepiness.