Background: Sleep difficulties are common among university students and may detrimentally affect academic outcomes. Despite this, remarkably little information is currently available during this critical developmental period of early adulthood, and thus, the direct effect on measurable domains of academic ability and proficiency is equivocal. Aims: To evaluate the associations between difficulties initiating and maintaining sleep (DIMS) and subjective and objective academic performance in a large sample of university students. Sample: A total of 12,915 students who participated in large student survey in Norway from 24 February 2014 to 27 March 2014. DIMS was assessed by the Hopkins Symptoms Checklist (HSCL-25), and academic outcomes included failed examinations, delayed study progress, and school-related self-efficacy (General Self-Efficacy Scale). Results: Difficulties initiating and maintaining sleep was independently associated with increased odds for poor school performance for all academic outcomes. Reporting "extreme" DIMS was associated with increased odds of reporting delayed study progress (adjusted odds ratio [OR] = 1.25, 95% CI 1.01-1.57, p < 0.05), increased odds for having failed several examinations (adjusted OR = 1.91, 95% CI 1.56-2.34, p < 0.001), and being in the lowest self-efficacy quartile (adjusted OR = 4.94, 95% CI: 4.04-6.03, p < 0.001). Conclusions: Self-reported sleep difficulties are associated with poorer objective markers of academic outcomes as well as poorer self-rated academic proficiency among higher education students. Amelioration of sleep difficulties may improve overall academic performance and health outcomes in affected students.