Tuesday, July 21, 1998 Published at 15:29 GMT 16:29 UK
Instant coffee, instant buzz
Coffee: the ultimate pick-me-up?
Not only does drinking coffee allegedly keep you awake and sober you up - scientists have found it can boost your attention, accuracy and alertness.
Research has shown that four cups of coffee - with the normal 65mg dose of caffeine - drunk over the course of a day has the same effect as a single large 200mg caffeine injection.
In both cases, people experienced an improvement in their performance, according to the study by researchers at Bristol University.
Attention, accuracy and reaction time improved as did feelings of alertness regardless of the way the caffeine was administered.
For the study, 24 male students were either given a 200mg dose of caffeine in coffee or four small doses of 65mgs, equivalent to that found in a cup of instant coffee.
The researchers, Carolyn Brice and Prof Andrew Smith, found that the two dosages led to the same saliva levels of caffeine.
Previous research has centred on the effects of caffeine following a single large dose - equivalent to a person's total daily intake.
Professor Smith said the effects would become greater as more caffeine was consumed during the day.
He added that the negative effects associated with caffeine, including anxiety, involved intakes three times the normal daily dose.
"One of the reasons why we drink it is probably that it is a very good way of restoring impairment produced by doing things over again," he added.