No lie-in! Teens need just seven hours sleep a night, study finds

Scientists from Brigham Young University in Utah examined pupils’ school performances and found that those who did best slept for seven hours.

Source: http://www.dailymail.co.uk/health/article-2100533/No-lie-Teens-need-just-seven-hours-sleep-night-study-finds.html?ITO=1490

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