Obstructive sleep apnea (OSA) has also been seen described in MS. Few case reports studies have reported that MS patients with OSA treated with continuous positive airway pressure (CPAP) had improvement in fatigue but not quality of life. Although the prevalence of OSA in the MS population is unknown, it may as much as twice as common as in the general population, which is 3 to 7%. Aside from the increased risk of daytime sleepiness, mood disorders, cardiovascular risk factors and accidents, OSA has also been implicated in increasing inflammatory markers like tumor necrosis factor (TNF-α). Elevation in TNF-α has also been seen in MS patients complaining of fatigue, which is thought to play a role in pathophysiology of fatigue in MS. The rational of this study is to determine if treatment of OSA with CPAP in MS patients improves fatigue. If effective, CPAP may not only decrease the risk of long term complications but may also improve the quality of life and daily living of these patients.