HRV Variation in Rheumatoid Arthritis

Inclusion Criteria:

* Diagnosis of RA meeting 2010 ACR/EULAR classification criteria
* Seropositive or seronegative RA eligible
* Any baseline disease activity (remission/low/moderate/high) to minimize selection bias
* Owns a compatible smartphone (iOS/Android) and is willing/able to use the Oura app
* Willing to wear Oura Ring during sleep throughout study participation (target adherence ≥5 valid nights/week)
* Willing to complete weekly remote assessments and attend baseline and three monthly routine follow-up visits
* Able to read and write English language
* Able to provide written informed consent

Exclusion Criteria:

* Atrial fibrillation or other clinically significant arrhythmias expected to invalidate HRV interpretation
* Implanted pacemaker/defibrillator where HRV measurements are unreliable
* Severe autonomic dysfunction likely to interfere with HRV interpretation (e.g., advanced diabetic autonomic neuropathy), per investigator judgment
* Recent major cardiovascular event within 6 months (e.g., myocardial infarction) or uncontrolled heart failure (NYHA class III-IV), per investigator judgment
* Current use of beta-blockers (excluded due to known autonomic/HRV effects)
* Pregnancy or planned pregnancy during the study period
* Inability to wear the ring reliably (e.g., occupational restrictions or hand deformity preventing wear)
* Participation in another interventional clinical trial likely to confound outcomes