WASHINGTON (AP) - Go ahead with that second cup of joe, soldier. Caffeine can help increase reaction time and improve performance for military servicemen who must perform complex tasks or who need help staying alert for longer periods of time, according to a new report by the National Academy of Sciences.

The report, by the academy's Institute of Medicine, found that 100 to 600 mg of caffeine, the equivalent of one to six cups of coffee, can help "maintain cognitive performance," especially in times of sleep deprivation.

"Specifically, it can be used in maintaining speed of reactions and visual and auditory vigilance, which in military operations could be a life or death situation," according to the report.

"We think this is going to be extremely important in this ongoing effort to combat terrorism," Lt. Col. Donald Archibald, deputy director of military operational medicine at Ft. Detrick, Md., said.

Americans can simply turn on a television "to see the amount of time and what the service members are being put through in terms of lack of sleep and stress," Archibald said. "Something that will boost their capabilities at crucial moments is very important."

Researchers are already exploring ways to put caffeine in nutrition bars or chewing gum as alternatives to coffee, Archibald said.

A similar dose of caffeine, about 200-600 mg, also appears effective in "enhancing physical endurance and may be especially useful in returning some of the physical endurance lost at high altitude," the study found.

The military also is considering other drugs, including modafinil, a drug sometimes used to counteract narcolepsy, that could help servicemen stay awake.

The Institute of Medicine is part of the National Academy of Sciences, a private organization chartered by Congress to advise the government on scientific matters.

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