Thou hast no figures nor no fantasies
Which busy care draws in the brains of men;
Therefore thou sleep’st so sound.
Julius Caesar (2.1.248-251)

Thus Shakespeare viewed people who cannot sleep. Sleep is the greatest gift to suffering humanity and the living creatures in this world. Sleep deprivation has been shown to give rise to transient behavioral changes, which is restored by a good sleep.

Why does one cannot sleep which is the commonest complaint with which patients present to a psychiatrist.  Turbulent mind (like that of King Lear) associated with anxiety and worry is a state of heightened brain activity (burning fire) which can never allow one to sleep.

The art of detachment from surroundings if mastered, any one can sleep anywhere, anytime as easily as water goes down the throat when one is thirsty.

Why detachment?  As religious scriptures proclaim that emotional attachment to our materialistic world is the root cause of suffering and misery. "Live in the present, bury the past and do not allow the future to take birth" also conveys the same idea. With this one can shut the shop totally till next day morning and can go to sleep well.

Total detachment gives rise to contentment and unique kind of joy which facilitate sleep.

Probably when there are no wishes in one's mind, sleep will be a dreamless one.

Such a sleep improves the general health of an individual and inturn increases the collective health of the society.

To sleep better "Live in one world at a time"