Effects of Frequency Adjustment in Functional Electrical Stimulation on Genioglossus Muscle Activity

Inclusion Criteria: * Adults aged 19 years or older * STOP questionnaire score ≥ 2 * Able to read and write in Korean * Voluntarily provides written informed consent to participate in the study Exclusion Criteria: * Refusal to undergo study procedures or failure to provide informed consent * Cognitive impairment or psychiatric disorders that interfere with the ability to follow study instructions * Pregnant or breastfeeding women * Known allergy or hypersensitivity to electrical stimulation pads or related materials (e.g., silicone, polypropylene, polyethylene) * Skin conditions preventing application of electrical stimulation (e.g., hypersensitive skin) * Medical conditions considered unsuitable for participation by the investigator (e.g., epilepsy, malignant tumor, high fever, diabetes mellitus, use of anticoagulants, phlebitis, thrombophlebitis, hemophilia) * Infectious disease or local conditions at the stimulation site (e.g., inflammation, wounds, abscess, edema) * Known cardiac disease or presence of a cardiac pacemaker or implanted electrical stimulation device * History of surgery involving the submental area or upper airway region