What hormone is released at night to help regulate the release of gonadotropin?

Melatonin is the hormone released at night that helps regulate the release of gonadotropin. It is produced by the pineal gland in response to darkness and plays a role in the circadian rhythm. Melatonin influences the hypothalamus, which in turn affects the secretion of gonadotropin-releasing hormone (GnRH), subsequently impacting the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. This regulation is crucial for reproductive health and the timing of puberty.