In addition to the typical motor and sensory impairments, individuals with multiple sclerosis (MS) often experience cognitive dysfunction and sleep disturbances. Cognitive impairment occurs in 40 % - 70% of patients with MS. In addition, sleep problems in individuals with MS are very common, and approximately 50% of patients with MS have a diagnosable sleep disorder. The research believes that aerobic exercise improve cognitive function and improve sleep quality.

Inclusion Criteria:

• diagnosis of relapsing remitting or secondary progressive MS
• score 3-7 on the EDSS
• score < 55 on the Symbol Digit Modalities Test
• score > 5 on the Pittsburgh Sleep Quality Index

Exclusion Criteria:

• history of alcohol/drug abuse or nervous system disorder other than MS
• severe physical, neurological, or sensory impairments that would interfere significantly with testing
• developmental history of learning disability or attention-deficit/hyperactivity disorder
• relapse and/or corticosteroid use within four weeks of assessment
• unable to give consent
• uncorrected vision loss that would interfere significantly with testing
• score less than 24 on MMSE
• Acute ischemic cardiovascular event or coronary artery bypass surgery less than 3 months ago
• Either unable to physically perform the exercise test using the recumbent stepper or demonstrate absolute indications for terminating exercise that follows the American College of Sports Medicine's (ACSM) guidelines
• Uncontrolled blood pressure with medication (BP > 190/110mmHg)