In what may be the largest study of sleep problems among individuals with multiple sclerosis (MS), researchers at UC Davis have found that widely undiagnosed sleep disorders may be at the root of the most common and disabling symptom of the disease: fatigue.

Conducted in over 2,300 individuals in Northern California with multiple sclerosis, the large, population-based study found that, overall, more than 70 percent of participants screened positive for one or more sleep disorders.

The research highlights the importance of diagnosing the root causes of fatigue among individuals with MS, as sleep disorders may affect the course of the disease as well as the overall health and well-being of sufferers, the authors said.