Bleary-eyed students will be aware that an extra hour in bed can help their studies in the day ahead, and now scientists have calculated the precise difference it?makes.

Their paper, published in , claims to?have quantified the exact relationship between total nightly sleep time and academic achievement in?the formative first year of?higher study.

For the study, researchers monitored more than 600 first-year US college students during the winter-spring term using Fitbits.

The wrist-worn devices recorded students across three universities sleeping for an average of six hours and 29?minutes on weeknights, and six hours and 58?minutes at weekends ¨C while also fitting in a daytime nap averaging 41?minutes. Bedtime on weekdays was typically 1.48am ¨C going as late as 2.33am at weekends ¨C with the average student lying in until 8.56am on weekdays, and 10.11am at the weekend.

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The researchers found that more sleep early in the term was associated with achieving a higher grade-point average (GPA) in end-of-term assessments, and that every hour of nightly sleep lost was associated with a 0.07?decrease on the four-point GPA scale. The effect was particularly pronounced if average nightly sleep dipped below six hours.

Only one in 20 study participants met the recommended minimum of eight hours of sleep a?night, and one in five slipped below the six-hour mark.

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The authors conclude that US students ¡°are getting insufficient sleep, and¡­it?may carry significant costs for their academic achievement¡±.

¡°First-year college students are making some of their first efforts to establish independent sleep habits, and often doing so amidst new competing pressures of work and dorm life activities, and a challenging academic course load,¡± they write.

¡°The present work highlights the importance of getting adequate early-term nightly sleep for academic achievement, suggesting that sleep behaviour interventions early in the academic term could be helpful for first-year college students.¡±

patrick.jack@timeshighereducation.com