The night owls showed greater activity in the master-clock region of their brains--a cluster of cells known as the suprachiasmatic nucleus--than the larks when taking the later test.

• 研究发现，做第二次测试时，相比早起型的人，夜猫子大脑的主生物钟区域的一组称为视交叉上核的细胞非常活跃。