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 discussing biological mechanisms and theory without primary empirical data
PubMed 36671781 · doi:10.3390/biology12010089
What was done
Narrative review examining multiple sources of vertebrate melatonin (pineal gland, extrapineal tissues, microbiota, and diet) and discussing the regulatory mechanisms by which non-visible solar radiation, specifically near-infrared (NIR) light, influences extrapineal melatonin production.
What was found
The abstract provides no numerical data. It describes that while visible light suppresses nocturnal pineal melatonin, daylight containing NIR radiation during exercise can elevate extrapineal melatonin, resulting in transient increases in sweat and plasma concentrations to counteract reactive oxygen species. It also notes high melanopsin levels in fat cells responding to light and points to potential host-microbiota melatonin crosstalk.
Why it matters
It challenges the conventional pineal-centric model of melatonin solely as a nocturnal circadian signal, highlighting a broader role for daytime, light-stimulated extrapineal melatonin in cellular homeostasis.
Limits
As a narrative review, it presents no primary clinical data, quantitative effect sizes, or systematic review protocol in the abstract. Precise regulatory mechanisms governing microbiota-derived melatonin and light-induced synthesis pathways remain incompletely defined.
Cited by
- context Infrared light induces melatonin synthesis within cellular mitochondria to clean up oxidative stress.