BACKGROUND: n-3 and n-6 polyunsaturated fatty acids (PUFAs) have physiologic roles in sleep processes, but little is known regarding circulating n-3 and n-6 PUFA and sleep parameters.OBJECTIVES: To assess associations between biomarkers of n-3 and n-6 PUFA intake with self-reported sleep duration and difficulty falling sleeping in the Fatty Acids and Outcome Research Consortium.METHODS: Harmonized, de novo, individual-level analyses were performed and pooled across 12 cohorts. Participants were between 35 to 96 years old and from 5 nations. Circulating measures included alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), EPA + DPA + DHA, linoleic acid and arachidonic acid. Sleep duration (10 cohorts, N = 18,791) was categorized as short (≤6 hours), 7-8 hours (reference) or long (9 + hours). Difficulty falling sleeping (8 cohorts, N = 12,500) was categorized as yes or no. Associations between PUFAs, sleep duration, and difficulty falling sleeping were assessed by cross-sectional multinomial logistic regression using standardized protocols and covariates. Cohort-specific multivariable-adjusted odds ratios (ORs) per quintile of PUFAs were pooled with inverse-variance weighted meta-analysis.RESULTS: In pooled analysis adjusted for sociodemographics and health status, participants with higher very long-chain n-3 PUFAs were less likely to have long sleep duration. Comparing top vs. bottom quintiles, the multivariable-adjusted OR (95% confidence interval, CI) for long-sleep was 0.78 (0.65, 0.95) for DHA and for EPA + DPA + DHA, 0.76 (0.63, 0.93). Significant associations were not identified for ALA and n-6 PUFA with short sleep duration, or difficulty falling sleeping.CONCLUSIONS: Participants with higher levels of very long-chain n-3 PUFAs were less likely to have long sleep duration. While objective biomarkers reduce recall bias and misclassification, the cross-sectional design limits assessment of the temporal nature of this relationship. These novel findings across 12 cohorts highlight the need for experimental and biological assessments of very long-chain n-3 PUFAs and sleep duration.