However, evidence also shows that near infrared radiation (NIR), which occupies a major portion of the wavelengths of sunlight, promotes melatonin production and the beneficial effects of sun baths or photobiomodulation therapy may be, at least, partially mediated by the increased local melatonin production induced by NIR. Unlike visible light, NIR can penetrate deep into the human body including the muscle, brain, and even the bones, and its effects on human biology remain to be clarified. Thus, the avoidance of light at night and exposure to sun during the day are equally important to improve melatonin production and human well-being.