b'lifestyle factors and health status every two years. In this study of 63,866 nurses (524 with MS), women with MS were more likely than those without MS to report obstructive sleep apnea, insomnia, and sleepiness. Furthermore, insomnia and sleepiness were each found to partially mediate relationships between MS and the self-reported ability to follow instructions/conversations/plots, and memory impairment four years later. Obstructive sleep apnea accounted for more than one-third of the total effect between MS and the ability to follow instructions four years latersuggesting sleep disorder as a potential key factor in the relationship between MS and cognitive decline. As interventions to delay cognitive decline in MS may be of the highest yield in early symptomatic stages, these ndings highlight a potential window of intervention for sleep-based methods to prevent perceived cognitive decline in MS. Fatigue and sleep disorders Fatigue affects up to 90 percent of people with MS, and is reported to be one of the most important symptoms. An extensive body of work has associated fatigue with sleep disturbances in people with MS. In a survey study of 195 people with MS, 46 percent reported symptoms of insomnia based on a commonly used screening tool, which showed strong associations with fatigue. In a separate study among people with MS and people without MS, people with MS who had suspected sleep problems were more likely than non-MS participants to emphasize problematic fatigue, tiredness, and lack of energy, as opposed to sleepinessa more commonly recognized signal for sleep problems. Furthermore, in people with MS only, reduced sleep efficiency was linked to increased symptoms of fatigue, suggesting that people with MS may be more sensitive to reduced sleep efficiency compared to people without MS. Data from a recently completed trial of three fatigue interventions on self-rated fatigue that also tracked daily MS symptoms showed that previous nights sleep duration was inversely linked to fatigue intensity and fatigue interference. People with MS with known or suspected obstructive sleep apnea have also been shown to exhibit higher levels of fatigue in various other studies. Although more work is needed, early trends suggest restless legs syndrome is also linked to MS fatigue.Pain and sleep disorders Pain affects approximately 50 percent of people with MS. Furthermore, sleep disturbances are closely associated with pain in MS. Numerous studies have identied pain as a predictor of poor sleep quality in MS. Sleep problems have also been shown to mediate relationships between pain and depression in MS. The same data from the previously referenced fatigue trial also showed that night to night variability in sleep predicts pain severity in people with MS, suggesting that pain and sleep may share a bidirectional relationship that requires further study. Additional research that demonstrates sleep problems as a predictor of pain could uncover new sleep-based targets for pain for people with MS.Medications may also cause a lack of sleep for some. While DMTs do not label sleep disturbances as one of their side effects, many people self-report sleeping disturbances while on certain DMTs. Other medications for comorbidities can also be causing issues with your sleep. If you are experiencing changes in your sleep 7'