Melatonin: Both a Messenger of Darkness and a Participant in the Cellular Actions of Non-Visible Solar Radiation of Near Infrared Light
Level 5 - mechanism / opinion, no new human data
Narrative review and mechanistic hypothesis paper without original clinical trial data
OpenAlex W4313575579 · doi:10.3390/biology12010089
What was done
This narrative review synthesized current evidence regarding four sources of melatonin in vertebrates: the pineal gland, extrapineal tissues, microbiota (skin, mouth, nose, digestive tract, and vagina), and diet. The authors discussed the potential regulatory mechanisms by which near-infrared (NIR) light and non-visible solar radiation stimulate extrapineal melatonin synthesis.
What was found
The abstract reports no primary experimental metrics or quantitative data. It describes that while retinal visible light suppresses pineal melatonin secretion, daylight containing near-infrared radiation combined with heavy exercise can increase extrapineal melatonin synthesis, leading to elevated concentrations in sweat and potentially circulating blood. It also highlights the presence of melanopsin in adipocytes and theoretical crosstalk between host and microbiota melatonin.
Why it matters
This paper challenges the conventional pineal-centric model of melatonin regulation, proposing that extrapineal melatonin functions locally to manage reactive oxygen species and maintain cellular homeostasis in response to solar radiation.
Limits
The abstract presents theoretical models and narrative synthesis rather than original human trial data, quantitative effect sizes, or a systematic search methodology.
Cited by
- supports Standard LED lights do not emit long-wavelength light such as near-infrared and infrared light, unlike sunlight, firelight, and some incandescent bulbs.