In normal circumstances, however, the SCN reacts to the lengthening nights by instructing the brain's pineal gland to secrete more of the hormone called melatonin.
然而，在正常情况下，SCN对夜晚延长的反应是，它会指示大脑的松果腺增加褪黑激素的分泌。
2
Melatonin, a hormone produced by the pineal gland in response to darkness, is thought to play a primary role in controlling the body's circadian rhythm.
褪黑激素，黑暗时松果腺产生的一种激素，被认为在控制身体昼夜节律起主要作用。
3
Melatonin is an important hormone synthesized and secreted by the pineal gland.