We searched the PubMed/MEDLINE databases for studies published in English between January 1990 and January 2020, using the following search terms: “light”, “circadian rhythm”, “chronodisruption”, “clock gene”, “melatonin”, “pineal”, “glucocorticoid”, “developmental programming”, “DOHaD”, “offspring”, “progeny”, “cardiovascular diseases”, “obesity”, “hypertension”, “neurological diseases”, “pregnancy”, “mother”, “maternal”, “gestation”, “neonatal”, “perinatal”, “light therapy”, “photobiomodulation”, and “reprogramming.”. Here, CLOCK is linked to obesity due to melanocortin 4 receptor deficiency.