Having multiple sclerosis is tough enough, but sleep problems on top of this devastating disease can actually worsen what’s known as “MS fatigue.” In fact, a new study suggests that these sleep problems might be the root cause of the fatigue.

The study ”The Under diagnosis of Sleep Disorders in Patients with Multiple Sclerosis” is published online today in the Journal of Clinical Sleep Medicine.” was conducted by researchers at the University of California, Davis, with Data for the study coming from more than 2,000 members of the Northern California Chapter of the National MS Society.

The study shows that people with MS also suffer from sleep loss, which increases fatigue. “A large percentage of MS subjects in our study are sleep deprived and screened positive for one or more sleep disorders,” said Steven Brass, associate clinical professor and director of the Neurology Sleep Clinical Program and co-medical director of the UC Davis Sleep Medicine Laboratory. “The vast majority of these sleep disorders are potentially undiagnosed and untreated.”

For the study, the researchers reportedly assessed the quality of sleep of 2,375 participants enrolled in the Northern California Chapter of the National MS Society. Consistent with previous findings, a majority of MS patients were females (over 80%).

“Researchers found that around 52% of the respondents said that it took them more than 30 minutes to fall asleep, with 11 percent saying that they used medications to sleep at night. Around 38% of the participants had obstructive sleep apnea, a condition that leads to severe snoring and frequent awakenings,” wrote Nature World staff writers. “About 32% of the people had moderate to severe insomnia and 37 percent had restless leg syndrome. What’s disturbing is that just four percent of the participants with OSA were actually diagnosed by a physician, meaning that common sleep problems go unnoticed and untreated in people suffering from MS.”