1 Introduction In the annals of time, the roots of photobiomodulation (PBM) stretch back to ancient civilizations. The Romans appreciated the benefits of sunbathing, even if they apparently did not attribute any therapeutic properties to it (Sequeira and O’Donovan, 1925). Herodotus, the famous Greek physician from the second century BC, was the father of heliotherapy. His teachings emphasized the usefulness of sun exposure for restoring health (Daniell and Hill, 1991).
