In normal circumstances, however, the SCN reacts to the lengthening nights by instructing the brain's pinealgland 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
This mechanism is associated with melatonin, a pigment secreted by the pinealgland, though scientists are not sure exactly how it operates.
该机制与松果腺分泌的一种色素---褪黑素有关，虽然科学家还不确定其如何起作用。
3
Melatonin, a hormone produced by the pinealgland in response to darkness, is thought to play a primary role in controlling the body's circadian rhythm.