Another austerity must be added to that of food, the austerity of sleep. It does not consist in going without sleep but in knowing how to sleep. Sleep must not be a fall into unconsciousness which makes the body heavy instead of refreshing it. Eating with moderation and abstaining from all excess greatly reduces the need to spend many hours in sleep; however, the quality of sleep is much more important than its quantity. In order to have a truly effective rest and relaxation during sleep, it is good as a rule to drink something before going to bed, a cup of milk or soup or fruit-juice, for instance. Light food brings a quiet sleep. One should, however, abstain from all copious meals, for then the sleep becomes agitated and is disturbed by nightmares, or else is dense, heavy and dulling. But the most important thing of all is to make the mind clear, to quieten the emotions and calm the effervescence of desires and the preoccupations which accompany them. If before retiring to bed one has talked a lot or had a lively discussion, if one has read an exciting or intensely interesting book, one should rest a little without sleeping in order to quieten the mental activity, so that the brain does not engage in disorderly movements while the other parts of the body alone are asleep. Those who practise meditation will do well to concentrate for a few minutes on a lofty and restful idea, in an aspiration towards a higher and vaster consciousness. Their sleep will benefit greatly from this and they will largely be spared the risk of falling into unconsciousness while they sleep.
Ref : On Education