Inclusion Criteria:
1. Age ≥ 18 years old
2. Body mass index ≤42 kg/m2
3. Prior documented diagnosis of OSA by means of a polysomnography (PSG) test or home sleep test (HST)
4. Documented evidence from a screening HST following consent to demonstrate:
1. AHI 15 - 50/hour
2. \>80% of the apneas and hypopneas are obstructive
5. Previous treatment attempt with CPAP resulting in failure to treat or discontinuation due to intolerance, subject choice, or struggle to use CPAP
6. Have not used CPAP or oral appliances within 1 week of the screening home sleep test and agree not to use CPAP or oral appliances throughout the study duration
7. Access to and ability to use a smart device such as a smartphone or tablet
8. Able to speak, read, and write English
9. In the opinion of the investigator, the subject will be able to understand and comply with all study procedures.
Exclusion Criteria:
1. Known sleep disorder other than OSA, such as narcolepsy, restless leg syndrome, idiopathic hypersomnolence or chronic insomnia
2. Craniofacial abnormalities that may be contributing to OSA
3. Previous surgery, injury, or radiation to the neck which, in the Investigator's judgment, could interfere with collar fit or comfort
4. Excessive hair or beard in the area of the neck where the collar will be placed, and/or unwillingness to shave that area for the duration of this study
5. Inflammatory skin condition, such as acne or eczema in the area where the collar will be affixed to the skin, which, in the Investigator's judgment, could interfere with collar fit or comfort
6. Known silicone allergy
7. Night shift work because of irregular sleep-wake cycles
8. Excessive alcohol intake, defined as that leading to interference with work, home life, or the ability to optimally perform normal everyday duties and tasks
9. Use of illicit drugs currently or within the past 5 years
10. Serious pulmonary disease (e.g., cor pulmonale, CO2 retention, or poorly controlled asthma)
11. Use of home oxygen or baseline oxygen saturation \<94%
12. Cancer that has been in remission for less than one year
13. Psychiatric illness that, in the opinion of the Investigator, is not reasonably well-controlled with treatment
14. Serious cardiac disease (e.g., congestive heart failure, unstable coronary artery disease, or poorly controlled rhythm disturbance)
15. Prior carotid endarterectomy, prior percutaneous coronary angiography (including any placement of carotid stents), or known stenosis of either internal carotid artery \> 70% from prior carotid imaging (e.g., carotid duplex ultrasound, angiography, computed tomography angiography, or magnetic resonance angiography)
16. Previous surgery for peripheral arterial disease
17. Presence of possible or definite carotid artery disease, defined as any of the following:
1. history of cerebrovascular accident (CVA) or transient ischemic attack (TIA) with uncertain etiology that is compatible with carotid artery disease
2. diminished carotid pulse on screening physical examination\*
3. \> 70% stenosis in either extra-cranial internal carotid artery as determined by duplex ultrasound\* (only performed on those who do not exhibit 17 a. or b.)
18. Tonsil size 3 or 4 (Appendix C)\*
19. Currently pregnant\* or planning to become pregnant during participation in this study
20. Unable to obtain adequate collar fit\*
21. Any condition or circumstance that, in the opinion of the investigator, may preclude study completion, interfere with accurate data collection, or bias the results
22. The investigator believes that the subject's participation may not be in his or her best interest
