There are people who are lucky enough in not having any difficulty in falling asleep. They absolutely have no trouble in dozing off the moment they hit the bed. And there is another category of people who lie simply staring at the ceiling. To toss and turn and wait for the mercy of the sleep to come would be the action of these people.
Sleep gets deprived when the normal progression and the order of the sleep stage is interrupted. The elderly, the women on their menopause stage and pregnancy are particularly prone to such deprivation and subsequently, become the losers of quality sleep.