Small, frequent doses of caffeine may be best for staying awake

Most people tank up on caffeine early in the morning, often ingesting up to 500 milligrams of the stimulant (the amount in a Starbucks grande coffee).

But if you need to stay awake for extended periods, a better way to stay sharp -- without suffering from sleepless nights -- might be to consume caffeine slowly and steadily, beginning halfway through the workday. This intake pattern can counteract the internal system that pushes the body toward sleep as the day wears on, new research has found. Early-morning consumption simply spikes caffeine levels in the blood and brain, which then drop off.

James K. Wyatt, now lab director of the sleep disorders center at Rush University Medical Center in Chicago, led a study of 16 healthy Boston men whose days were lengthened to 42.85 hours, including 25.57 waking hours. The schedule was meant to simulate the long shifts of emergency workers, military personnel and long-haul truckers.

Half the volunteers received a pill every waking hour containing the amount of caffeine in two ounces of coffee; the others received dummy pills. Researchers found that the small doses kept caffeine blood levels building steadily. They also found that the men who got the caffeine performed better on cognitive tests and were less likely to doze off than those who got the placebos.

To replicate the results without pills, Wyatt suggested a five-ounce cup of coffee (75 to 150 milligrams of caffeine) or an eight-ounce soda (45 to 50 milligrams) every couple of hours.

The findings were reported in the May issue of the journal Sleep.

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Jane E. Allen