Scientists and health experts have linked a lack of sleep to problems with concentration.
This is hardly surprising. Lack of sleep is quite physically stressful to the body. To compensate, we produce more stress hormones - adrenalin and cortisol - and these give us a boost over the short term. But persistent levels of these hormones can make you feel a bit jumpy - much like an excess of caffeine - and this reduces the ability to concentrate.
We all need enough deep, slow-wave sleep, so that the brain moves into Delta wave pattern, the sleep that restores us physically as well as mentally. For children, of whom we demand such a lot during the school years, this is especially important.
So much so that Glasgow City Council is asking a sleep counsellor, expert Nikki Cameron who works with Sleep Scotland, to work in four of its secondary schools.
Advice will include winding down schedules before going to bed, relaxation activities, and removing TVs and computers from bedrooms.
"Sleep is important for emotional and physical wellbeing, and for learning, because that is when memories are processed and the brain can store the learning," says Cameron.
They also cite research from the University of Minnesota that found A-grade students had, on average, 15 minutes more sleep a night than those achieving mainly B grades.
The same probably applies to the rest of us. If you want to concentrate better, make sure you're getting enough sleep.