Sleep is not a luxury, it's a necessity

TO SOME PEOPLE, sleep is a waste of time. Preferring a very busy daily schedule of business and social engagements, they only surren¬der to sleep when extremely tired. In contrast, others, enduring night after night of tossing and turning until the early hours of the morning, would give anything for a good night's sleep.

Why do some find it so hard to sleep, while others are desperate to stay awake? Should we view sleep as a luxury or a necessity? To an¬swer these questions, we need to understand what is going on while we are asleep.
The Mysteries of Falling Asleep

Exactly what makes a person lose con-sciousness and fall asleep remains a mystery. Researchers, however, have established that sleep is a complex process regulated by the brain and that it obeys a 24-hour biological dock.
As we get older, our sleeping habits change.