Fatigue is one of the most common symptoms in people with multiple sclerosis (MS), and a major cause for this is sleep deprivation. Sleep deprivation, while common in MS patients, often goes undiagnosed, according to a large population-based study conducted on more than 2,300 individuals. The research has been published online in the Journal of Clinical Sleep Medicine.

Conducted on MS patients in California, the study found that more than 70 percent of participants screened positive for one or more sleep disorders. Fatigue can significantly interfere with a person’s ability to function and may affect the course of the disease as well. The research was a means to highlight the importance of diagnosing sleep disturbances in MS patients.

"A large percentage of MS subjects in our study are sleep deprived and screened positive for one or more sleep disorders," said Steven Brass in a press release. He is the associate clinical professor and director of the Neurology Sleep Clinical Program and co-medical director of the University of California, Davis, Sleep Medicine Laboratory.

Most of these sleep disorders are also undiagnosed and untreated, according to Brass. "This work suggests that patients with MS may have sleep disorders requiring independent diagnosis and management," he said.

MS is an autoimmune disease affecting the central nervous system. Damage to the myelin, the insulating material around the nerve fibers of the brain and the spinal cord, interferes with the transmission of signals between the brain and different parts of the body, causing MS. While the exact cause is unknown, genetic and environmental factors are thought to trigger it.

The typical symptoms of MS include loss of vision, vertigo, weakness, and numbness. Patients also experience psychiatric symptoms. While the condition can be seen at any age, it is commonly diagnosed between ages 20 to 50.

Sleep disorders are very frequent in MS patients and some of the known causes are bladder dysfunction, due to which the person may have to wake up several times at night, or night time muscle spasms, or even depression.

To find out the prevalence of sleep disorders in MS patients, Brass and his colleagues surveyed members of the Northern California Chapter of the National MS Society, who were recruited in 2011.

Of the 11,000 participants interviewed, 2,375 were selected for the survey. Consistent with the reported epidemiology of multiple sclerosis, the majority (81 percent) were female and white (88 percent). The mean age of the participants was 54.

The participants were asked questions about their sleep history and factors which would affect sleep, such as obstructive sleep apnea, daytime sleepiness, insomnia, and restless legs syndrome.

Around 52 percent of the participants said it took them more than an hour to fall asleep and nearly 11 percent said they had to rely on medication to fall asleep. Close to 38 percent of participants screened positive for obstructive sleep apnea. While close to 32 percent were known to have moderate to severe insomnia, nearly 37 percent had restless legs syndrome. Moderate insomnia was experienced by nearly 25 percent of respondents.

A surprising find was that only around four percent of the patients reported being diagnosed with a sleep disorder by a physician even though close to 38 percent reported having obstructive sleep apnea. Other sleep disorders also showed poor statistics in diagnosis.

"Sleep disorder frequency, sleep patterns and complaints of excessive daytime sleepiness suggest that sleep problems may be a hidden epidemic in the MS population, separate from MS fatigue," Brass said.

Source: Brass S, et al. The Underdiagnosis of Sleep Disorders in Patients with Multiple Sclerosis. Journal of Clinical Sleep Medicine, 2014.