When the weekend comes,do you like to stay up late,then stay in bed for a long time the next morning?Many of us have different sleep habits on weekends.But scientists2 think these changes in sleep are bad for us,and could affect our health.And they say that sleeping at different times on different days is evidence3 of"social jet lag4".当周末到来时你会熬夜,然后第二天早上再赖床很久吗?我们很多人在周末都有不同的睡眠习惯。