Source Pravda.Ru

Small cups of coffee are more revitalizing

According to scientists at Harvard University, USA, a large cup of coffee in the morning gives you an initial boost that soon wears off. They say lots of small coffees are better at keeping you alert.

If you are a coffee drinker you should consider having lots of little cups of coffee during the day rather than a few big ones if you want to stay awake and alert throughout the day, say experts.

Caffeine interferes with the systems that govern our sleep. Our sleep duration, and when to sleep, is regulated by the circadian system and the homeostatic system. The circadian system detects night from day, it promotes sleep rhythmically, it works with the release of melatonin and some other hormones (our body clock) in a cyclical fashion. The homeostatic system tells us how much sleep we need. In other words, the circadian system tells us when to sleep and the homeostatic system tells us how long to sleep, reports

According to in the new study, the scientists instead tested the effects of administering an hourly, low dose of caffeine equivalent to about two ounces of coffee to one group, while the second group received a placebo. The caffeinated men performed better on cognitive tests than the control individuals did, and dozed off less often. And though they received the same cumulative dose as subjects in previous, single-dose studies, taking many small doses minimized some of the negative side effects that caffeine can have, such as tremors.

The findings strengthen the hypothesis that caffeine blocks a receptor for adenosine, a messenger involved in the homeostatic sleep cycle, but they also indicate that caffeine can’t replace the restorative effects of shuteye: although the caffeine-takers stayed awake more than the control group, they reported feeling sleepier. "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," Wyatt says, "particularly when someone has to remain awake longer than the traditional 16-hour wake episode."

"Most of the population is using caffeine the wrong way by drinking a few mugs of coffee or tea in the morning," said the centre's laboratory director, James Wyatt.

Researchers at Rush, along with others at Harvard Medical School, studied men in private suites, who had no way of knowing the time, for 29 days.

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