The scientific inquiry into the effects of Solfeggio frequencies on health is still in its infancy. Nevertheless, in a 2018 Japanese study, the authors looked at the effect of 528 Hz frequency on the endocrine system and autonomic nervous system. The results suggested that 528 Hz frequency had a strong stress-reducing effect, even after only five minutes of exposure.[3] Additionally, the study showed that music of different frequencies had different effects on the endocrine system.[3] This study is one of the first that provides scientific evidence supporting the use of Solfeggio frequencies as a form of sound therapy.