Study: Small Doses of Caffeine Best to Stay Awake

Are you often too tired for your afternoon or late-night workouts? A new study shows a better way to use caffeine to maintain energy levels:

Small, frequent doses of caffeine are best for truck drivers, doctors and others who need to stay awake over a long period of time, according to a U.S. study published Tuesday.


The regular doses of caffeine build up to counteract the body's natural desire for sleep and builds up the more one stays awake, the study said.


Small, frequent doses are more effective than a large jolt of caffeine in the morning, which wears off just as the body begins to feel the need for sleep, according to the study's lead author, James Wyatt.


"Most of the population is using caffeine the wrong way by drinking a few mugs of coffee or tea in the morning, or three cups from their Starbucks grande on the way to work," Wyatt, laboratory director of the Sleep Disorder Center at Rush University Medical Center in Chicago, said in a news release.


"This means that caffeine levels in the brain will be falling as the day goes on," he said. "Unfortunately, the physiological process they need to counteract is not a major player until the latter half of the day."


That process is the system that builds up the appetite for sleep. Caffeine is thought to block the receptor for adenosine, a critical chemical messenger involved in the body's drive for sleep, the report said.


Researchers at Rush, along with others at Brigham and Women's Hospital in Boston and Harvard Medical School (news - web sites), studied men in private suites who had no way of knowing what time it was for 29 days.


The men were scheduled to stay awake nearly 29 hours straight, simulating the amount of time some doctors, military and emergency services personnel have to up.


Those who were given a caffeine pill every hour equivalent to the caffeine in two ounces of coffee did better on tests than those who received an inert placebo, the study said. The subjects who took the caffeine pill also felt sleepier than the others when bedtime finally arrived, it said.


The research was published in the May issue of SLEEP, the journal of the Associated Professional Sleep Societies.


"While there is no perfect substitute for sleep, our results point the way toward a much better method for using caffeine in order to maintain optimal vigilance and attention, particularly when someone has to remain awake longer than the traditional 16-hour wake episode," Wyatt said.