The endocrine system is extensive, and secretes a great number of important hormones. For the purposes of this question, we will focus on the most important glands in the head, as these hormones regulate nearly every single function in the body.
The Pineal Gland releases Melatonin, a hormone which regulates the body's circadian rhythm, or sleep cycle. The Hypothalamus is located in the brain, and secretes several major hormones, including Dopamine, Oxytocin, and Growth-Hormone-releasing-Hormone, which allows the Pituitary Gland to release HGH, allowing the body to grow and mature. The Pituitary also releases Follicle-stimulating Hormone, which is an aid to sexual maturity, and beta-endorphins, which help manage pain; also Thyrotropin, which regulates the Thyroid. The Thyroid Gland releases Triiodothyronine, which regulates the basal metabolism, and Calcitonin, which stimulates bone growth.