Sauna Treatment for Long COVID

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 (Note: clinician judgment can override lack of positive COVID test with clear Long Covid onset and presentation) 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 known reasons other than PASC (e.g. longstanding diagnosis of Chronic Fatigue Syndrome pre-dating Long Covid, low thyroid, multiple sclerosis, AIDS related fatigue, mononucleosis), as determined by clinical discretion of study investigators 2. Known hypersensitivity to infrared heat exposure, significant history of heat stroke 3. Breastfeeding, pregnancy or planned pregnancy during study 4. Active suicidal intent 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)44 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. Back pain that would interfere with ability to lay on hard surface 10. Using medication that might impact thermoregulatory capacity and cannot be held for an appropriate length (at least one half-life) as determined by clinician judgment prior to receiving WBH treatment 11. Breast Implants 12. Claustrophobia that would interfere with ability to remain in sauna 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. History of hemophilia 16. History of febrile seizures or seizure disorders 17. Any new treatments/medications for long-COVID that have started in the past 3 months 18. A subject who in the opinion of the Principal Investigator would not be able to safely complete the study or would jeopardize study integrity.