MS patients who suffer from fatigue may actually have a sleep disorder, such as obstructive sleep apnea, restless leg syndrome, or insomnia.

A new study finds that more than 70 percent of people living with multiple sclerosis (MS) may also suffer from undiagnosed sleep disorders. Everything from sleep apnea to restless leg syndrome (RLS) might be contributing to fatigue — one of the most common symptoms reported by MS patients.

Using a detailed 10-page survey, researchers at the University of California, Davis Medical Center in Sacramento polled more than 2,300 members of the Northern California Chapter of the National MS Society about their sleep habits. They discovered that the majority of respondents screened positive for at least one sleep disorder.

MS patients may not suspect a bona fide sleep disorder as the cause of their daytime fatigue because fatigue has traditionally been considered one of the many symptoms of MS.

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Sleep apnea, RLS, daytime sleepiness, and insomnia were all sleep disturbances the researchers studied in order to find a link between a patient’s sleep health and the level of fatigue they experienced.

More than half of those who took the survey said it took them more than half an hour to fall asleep, with more than 11 percent resorting to medications to help them sleep. More than one-third of patients screened positive for obstructive sleep apnea, while another third suffered from insomnia. Almost 37 percent of patients had RLS.

However, most of them had never been diagnosed with a sleep disorder by a doctor.

“Sleep apnea has a Th1 cytokine profile that is similar to MS. MS is an autoimmune disease, but sleep apnea is not, but the impact of sleep apnea does have an impact on your immune system,” explained Dr. Steven Brass, co-medical director of the UC Davis Sleep Medicine Laboratory and lead author of the study in an interview with Healthline.

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Cytokines are substances secreted by cells that have an effect on the immune system. Th1 plays a role in allowing T-cells to do nerve damage in MS.

“What all the MS treatments do is they try to suppress the Th1 cytokines,” said Brass. Patients who have sleep apnea have a similar cytokine profile to MS patients, meaning that the same inflammation is present.

The standard treatment for sleep apnea is a continuous positive airway pressure, or CPAP, machine and face mask that is worn during sleep.

“When you treat [sleep apnea] with CPAP the TH1 cytokines drop,” Brass said, “so the question is, in patients with MS and sleep apnea, whether that would have a beneficial effect on the whole disease course — we don’t know.”

Brass points out that among patients who have sleep apnea but do not have MS, the most common word they use to describe their symptoms is “fatigue.”

“So MS can cause fatigue,” Brass concedes, “but it may not be the only answer. It can be other things.”

Is true MS-related fatigue caused by the loss of nerve conduction seen in MS? “A lot of people think that it is,” Brass said, “So you have to work twice as hard to do anything because of your demyelinated axons.”

But it could also circle back to Th1 cytokines, he said. “When you inject these same Th1 cytokines into mice, it will cause sleepiness,” Brass said.

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According to the National MS Society, about 80 percent of people with MS have fatigue. Still, the idea that MS patients might also suffer from sleep disorders is a relatively new angle for researchers to explore.

In 2011, Dr. Joseph Berger of the University of Kentucky published research that showed that some patients complain of fatigue as their major symptom long before MS is even suspected. Berger’s study suggests that fatigue should be considered a red flag that MS is a possible diagnosis.

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“I think that when MS patients present with fatigue, there needs to be an extensive evaluation of their sleep problem,” Brass said. He said that doctors often prescribe stimulants to people with MS who complain of fatigue rather than exploring the possible cause.

“I think basics need to be done,” he said, “like taking a sleep history, screening for sleep apnea, talking about sleep hygiene … I think it needs to be looked at better by MS neurologists in general and by other healthcare providers taking care of MS patients.”

For people living with MS, this study is good news — suffering from daytime fatigue doesn’t have to be a “given” simply because they have the disease. A doctor can refer a patient to a sleep specialist, who may recommend a sleep study to assess the patient’s quality of sleep. During the study, patients sleep in a room that is similar to a hotel room. As they sleep, their oxygenation, air flow, and eye movement are monitored.

The doctor can review your sleep study results with you and suggest a treatment plan.

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