And they don't ask a married couple with no children Why don't you have any children?.
他们也不会问结了婚没有孩子的夫妇“你们为什么不要孩子?”。
If it is not a question of resting the body, then perhaps it is the brain that needs resting? This might be a plausible hypothesis were it not for two factors.
如果睡眠的功能不是在于使身体得到休息,那么也许是让大脑得以休息?若不是下面两点,这种假使似乎是有道理的。