The goal of this study type: clinical trial is to evaluate adherence for CPAP used with wearable device in OSA patients comparing with controlled group; could include any of the following: adult patients (≥ 19 yr of age) with moderate to severe OSA (AHI ≥ 15 events/hr by polysomnography (PSG), according to the American Academy of Sleep Medicine, diagnosed at the sleep clinic in Ramathibodi hospital, patients with OSA who are first time to prescribed CPAP treatment and in the waiting process for their machine. The main question it aims to answer is: Could a wearable device help increase the adherence of CPAP in obstructive sleep apnea patients?

Primary outcome is adherence for CPAP: time usage per day(min) and % usage > 4 hours

Secondary outcome are access sleepiness and quality of sleep by questionnaire (ESS and PSQI) in Thai version, the correlation between wearable-derived and CPAP data: Total sleep time(min), sleep stage (light, deep and REM), and health information: heart rate, oxygen saturation, stress, sleep score and step counting

If there is a comparison group: Researchers will compare wearable group and control group to see the effect of wearable to increase adherence of CPAP used.

Participants will

• Divide into two group by randomization using 4 block randomization
• In wearable group, the participants will receive wearable and download application, they allow to access all the time
• In control group, the participants will receive wearable and download application, but they will not allow to access until they come to hospital for follow up at the end of the study

1. Lead-in Period Patients who have been diagnosed with moderate to severe obstructive sleep apnea and are scheduled to receive continuous positive airway pressure (CPAP) therapy will be referred to the Sleep Clinic, 7th Floor, Phra Thep Building, Ramathibodi Hospital. At this clinic, the research team will provide detailed information about the study. If the patient agrees to participate, written informed consent will be obtained. Participants will then be randomly assigned into one of two groups - the wearable device group or the control group - using block randomization. The allocation sequence will be prepared by a statistician and sealed in opaque envelopes to maintain allocation concealment. During this period, while waiting for CPAP device delivery from the supplier, participants will be asked to wear a Garmin Vivoactive 5 smartwatch to collect baseline data. They will also complete standardized questionnaires in Thai: the Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI) to evaluate baseline sleepiness and sleep quality.

2. Wearable Device Group (N = 40) Participants in this group will receive a Garmin Vivoactive 5 smartwatch and be instructed on its proper use. They will also learn how to access their health data via the Garmin Connect application, including sleep stages (light, deep, REM), heart rate, oxygen saturation, and daily step count. These data will be used to enhance patient engagement and support goal setting for personal health improvement. Participants will continue to receive standard education and counseling regarding CPAP use, with an emphasis on adherence and motivation to achieve optimal health outcomes.

3. Control Group (N = 40) Participants in this group will also receive a Garmin Vivoactive 5 smartwatch but will be informed that access to health data through the application will only be available during follow-up visits at the hospital, including the final follow-up visit. Participants will not have direct access to the application, as login requires a password controlled by the research team. If a participant connects the device to another account, the research team will be able to detect it due to the creation of a new user profile, resulting in incomplete data continuity. Patients will be able to view limited on-screen information, such as average oxygen saturation, sleep score, and step count. The screen brightness will be adjusted to the lowest level to minimize light exposure during sleep. They will also receive standard CPAP education identical to the intervention group, encouraging consistent device use for optimal treatment benefits.

4. Follow-Up Procedures 4.1 Week 1 and 2 (Line call/video call Follow-Up) All participants will be contacted by Line call/video call at Week 1 and 2 to assess CPAP adherence, address difficulties, and provide additional guidance to promote usage of at least 4 hours per night. Participants in the wearable group will be asked to capture screenshots from their Garmin Connect app and send them via the Sleep Center's official LINE account. The data collected will include sleep stage distribution, total sleep time, heart rate, oxygen saturation, sleep score, and step count.

   4.2 Weeks 4 and 8 (Clinic Follow-Up) At Weeks 4 and 8, participants will attend in-person follow-up visits at the Sleep Clinic.

   Data collected will include:

   • From Garmin Connect: sleep stage, total sleep time, HR, oxygen saturation, sleep score, step count.
   • From CPAP device downloads: average usage time per day (minutes), % nights used >4h, AHI, leak, and pressure levels. At Week 8, participants will again complete ESS and PSQI (Thai versions) to evaluate post-intervention outcomes.

5. Data Management and API Integration During the study, the research team will request access to Garmin Health API for raw data retrieval, which may be used for further research analysis or development of a web-based application for patient monitoring.

6. Data Collection and Analysis All collected data will be compiled, cleaned, and analyzed according to the predefined statistical plan.

7. End of Study Procedure At the end of the 8-week study period, participants will return the Garmin Vivoactive 5 smartwatch. The research team will verify data completeness, clean and reset the devices, and prepare them for use by subsequent participants.

Inclusion Criteria:

• Adult patients (≥ 19 yr of age) with moderate to severe OSA (AHI ≥ 15 events/hr at the sleep clinic in Ramathibodi hospital
• Study after EC approval to March, 2026
• Patients with OSA who are prescribed CPAP therapy and accepted a trial of therapy

Exclusion Criteria:

• Patients deny to provide an informed consent
• Patients had active cardiovascular, pulmonary, psychiatric disease, and epilepsy
• Patients had been previously used CPAP for treatment of OSA
• Patients have a problem to use a wearable device or watch
• Patients had used any smartwatch before
• Patients do not have a smart phone