Resting Heart Rate Monitoring for Optimized Treatment and Surveillance of Hyperthyroidism

Inclusion Criteria: All participants: * BMI 17 to 35 kg/m2 * Diagnosis of Graves' disease (matching one of the following criteria: elevated TRAb and/or ultrasonography and functional imaging consistent with Graves' disease) * In possession of a smart phone * Able to use a wearable device and willing to regularly upload their biometric data * Informed consent as documented by signature (Appendix Informed Consent Form) Group "treatment": * TSH \< 0.2 mIU/l and * fT4 \> 25 pM or fT3 \> 8 pM * ATD planned, additional treatment with propranolol allowed Group "surveillance": * TSH within the reference range between 0.3 and 4.5 mlU/l * Cessation of ATD is planned within the next 2-4 weeks Exclusion Criteria: * Chronic treatment with beta blocker or verapamil-type calcium antagonist for other reason than symptomatic treatment of hyperthyroidism (propranolol) * Treatment with amiodarone * Pacemaker with continuous stimulation. * Severe concomitant diseases: chronic heart failure, liver cirrhosis, kidney failure, active cancer * Abuse of alcohol or illicit drugs * Allergic to nickel or silicone * Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant