As the world goes dark, this master switch tells our pineal gland to increase levels of the hormone melatonin in the bloodstream, sort of like a chemical lullaby.
Mother, dear mother, the years have been long Since I last listened your lullaby song; Sing, then, and unto my soul it shall seem Womanhood's years have been only a dream!
Across countries and cultures, for instance, lullabies tend to share similar acoustic features that imbue infants and adults alike with a sense of safety.