Millions of people rely on strong coffee every morning to really wake up. All-night truck drivers sometimes take amphetamines to stay conscious on the road, and for centuries South American peoples have chewed coca leaves to stay alert and increase physical endurance. Yet none of these compounds are specific “consciousness” drugs. They stimulate waking along with many side effects. A novel pharmaceutical, modafinil (provigil), may be the most specific consciousness-promoting drug yet.

A drug designed to help people with a particular sleep disorder to stay awake could soon be licensed to perk up sleepy shift workers and others affected by drowsiness. The prospect is stirring up a debate about the dangers of popping a pill to counter a sleep-deprived lifestyle.

Provigil, as the drug is known in the US and Britain, is approved for treating the daytime sleepiness associated with the rare condition called narcolepsy, which makes people fall asleep involuntarily. But last week, the drug's manufacturer, Cephalon of West Chester, Pennsylvania, announced results from a clinical trial of 209 shift workers that showed it helps those with "shift work sleep disorder" - excessive sleepiness caused by odd working hours.