Melatonin production is triggered by dimming and color-changing light, signaling the body to initiate nighttime activities and regulate metabolism.

“So it is the perception of light by the eye which is eventually the trigger to say, "Okay. It's becoming dark. Produce melatonin." And then melatonin, we think of that as a sleepiness hormone, but it has fairly weak soporific activity, which means it's not a very strong stimulator for sleep, but it's more of a reinforcer that it is in fact dark out. And so it's telling all the clocks within the suprachiasmatic nucleus, "Yeah, it's now nighttime. Do nighttime activities." So it will affect the transcription and the translation activity that's happening.”