Sleep has been directly linked to the grades of students. One in four U.S. high school students admit to falling asleep in class at least once a week. Consequently, results have shown that those who sleep less do poorly. In the United States sleep deprivation is common with students because almost all schools begin early in the morning and many of these students either choose to stay awake late into the night or cannot do otherwise due to delayed sleep phase syndrome. As a result, students that should be getting between 8.5 and 9.25 hours of sleep are getting only 7 hours. Perhaps because of this sleep deprivation, their grades lower and their concentration is impaired. As a result of studies showing the effects of sleep deprivation on grades, and the different sleep patterns for teenagers, a school in New Zealand, changed its start time to 10:30 a.m., in 2006, to allow students to keep to a schedule that allowed more sleep. In 2009, Monkseaton High School, in North Tyneside, had 800 pupils aged 13–19 starting lessons at 10 a.m. instead of the normal 9 a.m. and has reported that general absence has dropped by 8% and persistent absenteeism by 27%. Similarly, a high school in Copenhagen has committed to providing at least one class per year for students who will start at 10 a.m. or later.

Sleep-learning (also known as sleep-teaching, hypnopædia, or hypnopedia) attempts to convey information to a sleeping person, typically by playing a sound recording to them while they sleep.

This technique is supposed to be moderately effective at making people remember direct passages or facts, word for word. Since the electroencephalography studies by Charles W. Simon and William H. Emmons in 1956, learning by sleep has not been taken seriously. The researchers concluded that learning during sleep was "impractical and probably impossible." They reported that stimulus material presented during sleep was not recalled later when the subject awoke unless alpha wave activity occurred at the same time the stimulus material was given. Since alpha activity during sleep indicates the subject is about to awake, the researchers felt that any learning occurred in a waking state.

See also: https://en.wikipedia.org/wiki/Sleep_and_learning

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