The appraisal of sleep quality not only lies on the length of sleep time, moreover also on the speed of falling into sleep and the depth of sleep, as well as whether the sleep structure is reasonable.

评价睡眠质量不仅仅在于睡眠时间的长短，而且还包括入睡的快慢、睡眠的深度，以及睡眠结构是否合理。

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This increases your frequency and depth of REM sleep, viewed by experts as the most rejuvenating level of slumber.

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