Fainting Detection And Early Warning In Syncope Evaluation Study (ARISE)

Inclusion Criteria: * Willing and capable to provide informed consent * Age 18 or above * Previously underwent a clinically indicated ARS assessment without complications (including deep breathing, Valsalva maneuver, and tilt table testing). * Previously diagnosed with OH, Vasovagal syncope, OR control subjects assessed as normal, based on the ARS assessment. Participant enrollment shall be based on the type of diagnosis. * Willing to complete all required study activities. Exclusion Criteria: * Currently enrolled in another clinical trial that might interfere with data collection. * Subject is pregnant or planning to become pregnant during the study * Active Implantable Medical Device, e.g. cardiac implantable electronic devices, bladder stimulators, diaphragm stimulators, implantable neuro stimulator, implantable active monitoring devices, implantable active drug administration devices, etc. * Have a prosthetic cardiac valve or previously underwent cardiac valve surgery. * Known allergy to materials used in the study (adhesive, ECG electrodes) * Diagnosed with syncope due to cardiologic causes. * Have had a myocardial infarction in the previous 90 days * Have been diagnosed with tachycardia that requires current medical treatment * Have any contraindications for exercise testing, tilt table test, Valsalva maneuver test or deep breathing test (judged by the study Principal Investigator)