Optimizing Extended-Duration (XD-) TOMAC Therapy for Restless Legs Syndrome (RLS)

Inclusion Criteria: * Subject has signed a valid, IRB-approved informed consent form, can understand the requirements of the study and instructions for device usage, and can converse in English * Subject has received a medical diagnosis of primary restless legs syndrome (RLS). * Subject agrees to not change dosage or schedule of any medications that are known to impact RLS symptoms during the study, including RLS medications, antidepressants, sleep medications, or sedative antihistamines or treatments such as CPAP (continuous positive airway pressure). * Subject reports that RLS symptoms are most significant in lower legs and/or feet. * Subject reports that RLS symptoms caused awakenings or interfered with falling back asleep at least 3 nights per week during the month prior to study entry. * The subject possesses the necessary equipment, internet/phone accessibility, and communication ability to complete electronic questionnaires and respond to electronic communications and phone calls from the research staff throughout the in-home portion of the study. * Subject has moderate-severe RLS symptoms as defined by a score of 15 or greater points on IRLS (International Restless Legs Syndrome Study Group Rating Scale). * Subject is 21 years of age or older. Exclusion Criteria: * The subject has an active medical device implant anywhere in the body (including but not limited to pacemakers, spinal cord stimulators, deep brain stimulators). * The subject has a metal implant at the site of the study device electrode application (not including knee replacements). * The subject has been diagnosed with epilepsy or other seizure disorder. * The subject has a moderate or severe cognitive disorder or mental illness that would affect his or her ability to participate in the study. * The subject has a known allergy to device materials, electrode gel, polyurethane foam, or lycra (or a severe previous reaction to medical adhesives or bandages). * Subject has any of the following at or near the location of device application: Acute injury, Cellulitis, Open sores * The subject is unable or unwilling to comply with study requirements. * The subject has a medical condition not listed above that may put them at risk. * Subject has prior experience with neurostimulation devices developed by the study sponsor * Subject has a primary sleep disorder other than RLS that significantly interferes with sleep at the present time (e.g. obstructive sleep apnea stably controlled via CPAP would not be an exclusion). * On nights with no RLS symptoms (if any), subject reports typical sleep onset latency of \>60min. * Subject has severe peripheral neuropathy affecting the lower legs and/or subject has neuropathy and is unable to clearly distinguish between symptoms of neuropathy and symptoms of RLS. * Subject reports a habitual sleep schedule that is not primarily aligned with nighttime hours (bedtime 8:00pm-2:00am and morning awakening 4:00am-11:00am), or reports that bedtime regularly varies by more than 4 hours (e.g., due to shift work or an inconsistent sleep schedule). * Subject is taking an unstable or inconsistent dose or schedule of medication that is likely to impact RLS symptoms or sleep, such as RLS medications, antidepressants, sleep medications, or sedative antihistamines. * Subject has changed dose or schedule of medication or treatment that is likely to impact RLS symptoms or sleep in the past 30 days, such as RLS medications, antidepressants, sleep medications, or sedative antihistamines or treatments such as CPAP. * During initial device set-up, device does not properly fit the subject or calibrated intensity settings are outside of operational range