If the most health-conscious among us have such deep swings in our shut-eye levels throughout the year, how much sleep are the rest of us losing?

2015年12月四级真题（第三套）阅读 Section C

Some 40% of Americans get less than seven hours of shut-eye on weeknights.

2016年6月四级真题（第一套）听力 Section C

It's no surprise, then, that more than half of American adults don't get the 7 to 9 hours of shut-eye every night as recommended by sleep experts.

2015年12月六级真题（第二套）阅读 Section A