When dopamine levels are low, the body produces lower levels of endorphins ) (a natural painkiller), making the person feel like the world is a dark and unhappy place.

• 当多巴胺处于低水平时，身体产生的内啡呔(一种天然的止痛剂)也会减少，这会使人感到世界竟是如此阴郁、令人悲伤。