• INCLUSION CRITERIA:

To be eligible to participate in this study, an individual must meet all of the following criteria:

• Stated interest in, and availability for, participating in NCCIH studies and willingness to comply with the procedures of this protocol.
• At least 12 years of age
• No identified acute health concerns (i.e. symptomatic uncontrolled diabetes mellitus, congestive heart failure, liver cirrhosis, ongoing cancer (excluding skin basal cell carcinoma and squamous cell carcinoma) as evidenced by screening medical history
• Ability to understand and able to provide written informed consent form.

EXCLUSION CRITERIA:

An individual who meets any of the following criteria will be excluded from participation in this study:

• Have active medical or psychiatric health issues that create additional and substantial adverse risks related to study procedures. Medical examples are the acute complications of medical disease, such as asymptomatic hypertensive urgency, diabetic ketoacidosis, symptomatic hyperthyroidism, and unstable angina. Psychiatric examples are the acute complications of psychiatric disease, such as acute mania, paranoid delusions, or having active panic attacks.
• Ongoing substance uses disorder or illicit substance use
• Pregnancy

Additional exclusion from optional QST procedures:

Has a major medical condition or medical history that in a clinician's assessment could affect heat sensitivity, pain thresholds, or ability to comply with study procedures. This may include cardiovascular, autonomic, or neurological conditions (including stroke and blindness or deafness, a history of brain damage, or psychosis).