Lights are everywhere and are used daily but there are proven links to negative health effects from different types of lighting.
The most widely used lights (LEDs) are shown to have a presence of arsenic, lead and other toxic substances in them. Currently, there is no standardized regulations and guidelines for the quality and safety of LED lightIng. A study published in late 2010 in the journal Environmental Science and Technology Showed some of the worst LEDs were low-intensity red LEDs, which were found to contain up to eight times the amount of lead, a known neurotoxin, allowed by California state law which, “exhibit significant cancer and noncancer potentials due to the high content of arsenic and lead.” White LEDs were found to contain the least led but are known for causing eye strain, headaches, migraines, and potentially irreversible damage to the retina.
With older light sources of mercury vapors, fluorescent, sodium vapors, gas discharge lamps, there are dangers as they have photon emissions below 400nm with blue rays and lower, up to about 250nm of the UVA and UVB. These emissions can cause eye damage and even up to cancers due to the use of the mercury. Mercury is banned in the EU because of this.
One light source that has not been linked to have any negative effects on health are Incandescents. Some suggest Incandescents have an increased risk of flickering, which would have a negative impact on health, but Incandescent bulbs use a filament to produce light which emits a steady stream without flicker. No toxins or hazardous materials are used to make incandescent bulbs and none have been found in them
2010 study:
https://pubs.acs.org/doi/abs/10.1021/es101052q?prevSearch=irvine%2Bled#