Sleep apnea not only reduces sleep quality and makes people feel tired during the day.

VOA: special.2011.05.04

Probably the best answer is our body is worn out during the day and sleep is necessary to put it back into shape.

最佳的答案应该是,一天下来，我们的身体已经疲惫了,有必要进行睡眠，以恢复状态。

耶鲁公开课 - 心理学导论课程节选

And take brief naps during the day to get extra sleep.

VOA: special.2010.06.09

Sometimes people sleep for a short time during the day.

VOA: special.2009.09.27