Sleep Based on Today's Reality

In the last decade, researchers have begun studying sleep based on today's reality: a country, such as the US, open for business virtually 24/7, and people increasingly unwilling or unable to call it a day. Sleep needs vary slightly, but the vast majority of people, experts agree, need just about eight hours of sleep each night to fully recover from 16 hours of being awake.

Yet, people are racking up sleep debt like a college kid with a credit card. About 40 per cent of Americans say they get fewer than seven hours of sleep on weekdays, and most - 71 per cent - get fewer than eight hours of sleep, according to a 2005 survey by the National Sleep Foundation.

Even on weekends, they sleep about seven and a half hours - better, but not enough to pay back the week's loss. Every hour they fall behind is considered an hour of sleep debt, and Americans accumulate about two full weeks of personal sleep debt a year.