Prayer's effects on health have been studied many times.
Small studies initially reported some benefit, but more rigorous studies found null or even harmful effects.
In sum, prayer seemed ineffective, recommending focus on more promising interventions: https://doi.org/10.1002/14651858.CD000368.pub3
Notably, some of the investigators had "a prior belief in the positive effects of #prayer" (Benson and Byrd) and nonetheless found plenty of null results, or results that hovered on either side of the null (p. 16, 👆).
🔓 https://pmc.ncbi.nlm.nih.gov/articles/PMC7034220/pdf/CD000368.pdf
