Inclusion Criteria:

• 1. 18-65 years of age
• 2. English language proficiency
• 3. Ability to provide informed consent
• 4. Ability to lie supine (on back) for 2 hours (required for sauna sessions)
• 5. Must have had clinically suspected COVID-19 and a positive antibody test or a documented SARS-CoV-2 infection (a positive reverse transcription polymerase chain reaction test) at least 12 weeks prior to Screening
• 6. The Patient Reported Outcome Measurement Information System Fatigue-Short Form v1.0 -Fatigue 7a (PROMIS F-SF43) raw score of 21 or greater at Screening (onset of fatigue confirmed post-infection as in other studies of PASC)
• 7. Individuals of childbearing potential must use an acceptable form of birth control.

Exclusion Criteria:

• 1. Fatigue for reasons other than PASC
• 2. Known hypersensitivity to infrared heat exposure
• 3. Breastfeeding, pregnancy or planned pregnancy during study
• 4. Active suicidal intent ("yes" on item 4 or 5 on the Columbia-Suicide Severity Rating Scale44)
• 5. History of bipolar disorder, psychotic disorders, eating disorders, obsessive compulsive disorder, and/or substance use or dependence (within the last year), as per the Mini-International Neuropsychiatric Interview (MINI)45
• 6. Positive urine toxicology screen for illicit drug use
• 7. Any serious unstable medical condition
• 8. Inability to fit into the sauna device. Morbid obesity (BMI \> 40) and/or body shape that might increase the risk of cutaneous burning from the device (because of skin being too close to the heat).
• 9. Using medication that might impact thermoregulatory capacity within 3 days of receiving WBH treatment (e.g., diuretics, barbiturates, beta-blockers, antipsychotic agents, anti-cholinergic agents or chronic use of antihistamines, aspirin (other than low-dose ASA for prophylactic purposes), non-steroidal anti-inflammatory drugs (NSAIDs), systemic corticosteroids, selective serotonin reuptake inhibitors \[due to potential interference with effect of WBH36\], or cytokine antagonists)
• 10. Breast Implants
• 11. Claustrophobia that would interfere with ability to remain in sauna
• 12. Fever (Temp \> 99 degrees Fahrenheit) of unknown origin at the time of screening
• 13. Unsafe cardiac status as defined by abnormal ECG reading at screening visit or as determined by study doctor or subject's physician
• 14. History of or current diagnosis of thrombosis or thrombophilia
• 15. A subject who in the opinion of the Principal Investigator would not be able to safely complete the study or would jeopardize study integrity.