Provigil "reduced extreme sleepiness" and made a "small but significant" improvement in the workers' job performance when compared with a fake drug (placebo), write the researchers in The New England Journal of Medicine.
"However, the residual sleepiness that was observed in the treated patients underscores the need for the development of interventions that are even more effective," they write.
The study was sponsored by Cephalon, which makes Provigil. The researchers included Charles Czeisler, MD, PhD, of the sleep medicine divisions of Harvard Medical School and Boston's Brigham and Women's Hospital.
"Nearly 6 million Americans work at night on a permanent or rotating basis," write the researchers. They estimate that 5% to 10% of night-shift workers have shift-work sleep disorder.
Symptoms include excessive sleepiness during night work and insomnia when trying to fall asleep during the day.
The study included 209 night-shift workers. They were randomly given 200 milligram doses of Provigil or a placebo for three months. The workers didn't know which pill they got; 153 workers finished the study.
Patients were asked to report any use of over-the-counter sleep aids. Five of the 96 people taking Provigil reported using over-the-counter sleep aids, compared with one of the 108 patients taking the placebo.
Less Sleepiness on the Job
Symptoms improved in nearly 75% of patients taking Provigil, compared with 36% of those taking the placebo.
Workers taking Provigil had fewer and shorter lapses of attention on the job. They also fell asleep a bit quicker when they tried to fall asleep, but only by about two minutes, write the researchers.
Sleepiness can be a major hazard for commuters. The number of patients who had accidents on the way home from work was 25% lower in the Provigil group.