Safety on the road, concentration in the class and safety in all other activities is of prime importance. To be safe means not to do things that can cause yourself or others damage. When you are walking or working half asleep, you become a walking or a working time bomb. If you are in a vehicle you become a driving time bomb. It also causes serious physiological changes that are deleterious to health.
Teenagers have to be told that sleeping is as important as eating and breathing.
Tossing and turning acts as a signal to the body that you're ready to get up. Do not go to bed until you're really sleepy. Warm milk with one or two teaspoons of honey. Warm milk contains tryptophan. Tryptophan is an essential amino acid.