$课文19 话说梦的本质

285. It is fairly clear that sleeping period must have some function,

很清楚，睡眠必然具有某种作用。

286. and because there is so much of it the function would seem to be important.

睡眠占去那么多时间，所以其作用似乎还是很重要。

287. Speculations about is nature have been going on for literally thousands of years,

人们对睡眠作用的种种猜测，确实有数千年之久。

288. and one odd finding that makes the problem puzzling is that it looks very much as if sleeping is not simply a matter of giving the body a rest.

一项使人对这个问题感到困惑的奇怪的发现是，睡眠在很大程度似乎并不仅仅是为了使身体得到休息。

289. ’Rest’, in terms of muscle relaxation and so on,

“休息”，从使肌肉得到放松等方面来看，

290. can be achieved by a brief period lying, or even sitting down.

只要稍微躺一躺，甚至坐一坐就能达到。

291. The body’s tissues are self-repairing and self-restoring to a degree,

人体组织在一定程度上有自我修补和自我恢复的能力，

292. and function best when more or less continuously active.

有张有弛地连续活动时，其功能最佳。

293. In fact a basic amount of movement occurs during sleep

事实上，睡眠状态下仍有着基本的活动量，

294. which is specifically concerned with preventing muscle inactivity.