b'People who experience insomnia symptoms three or more times per week for at least three months may suffer from chronic insomnia disorder. Although certain symptoms that are commonly encountered in MS (including depression, pain, spasticity, and bladder problems) may increase the risk of insomnia, many non-MS related causes, including other sleep disorders, also increase this risk.Insomnia is closely linked to fatigue, cognitive problems, and worse quality of life. Evaluation with a sleep specialist is recommended for persistent or problematic symptoms to properly characterize the cause and type of insomnia, rule out other sleep-related conditions, and provide treatment recommendations that may include cognitive behavioral therapy.Restless legs syndrome is a condition that is associated with an uncomfortable sensation in the legs, or less likely the arms, during periods of inactivity or rest, usually after prolonged sitting and during the evening hours. These symptoms, by denition, should be relieved by voluntary movement of the limbs, even if relief is only temporary. Restless legs syndrome is at least three times more common in people with MS as compared to the general population, possibly because of neuroanatomical changes linked to MS. Low iron levels are another potential cause, not unique to MS. Other symptoms that commonly affect the legs, including spasticity and neuropathic pain, can mimic restless legs syndrome. An overnight sleep study is not required to diagnose restless legs syndrome. However, a sleep study may be recommended if another sleep disorder is also suspected that could worsen or mimic restless legs syndrome. Treatments primarily include iron supplementation and medications, but other nonpharmacological treatments including exercise also hold promise.Cognitive function and sleep disorders Impairments in cognitive function (e.g., cognitive dysfunction) affect up to 70 percent of people with MS, and cognitive dysfunction is considered to be one of the most disabling symptoms of MS. Despite its prevalence and effect, interventions to minimize or improve cognitive dysfunction in MS are limited. Several sleep disorders have been linked to both self-reported and objective measures of cognitive function. In one of the rst studies to evaluate relationships between objective sleep measures (using data from overnight sleep monitoring) and objective cognitive testing, investigators from the University of Michigan showed that people with MS who had greater sleep apnea severity performed worse on tests that measured verbal memory, working memory, processing speed, attention, and visual memory.The ndings were later observed in a larger, follow-on study. In addition to nding similar relationships between sleep apnea measures and performance on tests that assessed working memory, processing speed, attention, and visual memory, worsening apnea severity was also associated with decreased cognitive exibility, manual dexterity (hand control/coordination), and visuomotor coordination, raising the possibility that sleep disturbances could affect performance across multiple cognitive domains in MS. More recent research offers insight into how sleep and MS work together to affect perceptions of cognitive decline. To examine this relationship, data from a large dataset of women nurses from the Nurses Health Study were analyzed. The NHSisanobservationallong-termstudyin whichnursesaresurveyedabout 6'