But now experts have found that it is 7 hours that brings optional health-and that more or less sleep may do us harm.

然而专家发现，7小时才是黄金睡眠时间，睡多睡少都会有损健康。

youdao

But now experts have found that it is 7 hours that brings optional health-and that more or less sleep may do us harm.

然而专家发现，7小时才是黄金睡眠时间，睡多睡少都会有损健康。

youdao