Scientists say that people who mix energy drinks with alcohol may feel more sober but that perception is a delusion.

A new study has found that although the combination of alcohol and the energy drink Red Bull made drinkers feel less drunk they were in fact just as impaired as when they consumed standard mixed drinks.

In experiments with young male volunteers, Brazilian researchers found that the men were no less impaired when they drank a mix of alcohol and the energy drink Red Bull.

Although the study found that drinking alcohol and Red Bull together significantly reduced the perception of headache, weakness, dry mouth and impairment of motor coordination, the alcohol’s harmful effects on motor coordination, remained intact.

The researchers say it is a concern because people who combine alcohol with energy drinks may be at even greater risk for problems such as automobile accidents because they believe they are more sober than they really are.

The practice of combining alcohol and energy drinks such as Red Bull has become increasingly popular among youth and young adults in recent years, and users often report reduced sleepiness and increased sensations of pleasure.

Apparently in Brazil, and in other countries, young people believe that Red Bull and other energy drinks avoid the sleepiness caused by alcoholic beverages and increase their capacity to dance all night.

According to study co-author Dr. Maria Lucia O. Souza-Formigoni, people need to be aware that even though they feel better they should not attempt to drive.

Souza-Formigoni, associate professor in the department of psychobiology at the Federal University of Sao Paulo in Brazil says many night clubs offer this mix among their cocktails.

The new study suggests that while energy drinks may help tipplers feel less tipsy, they are still in fact drunk.

For the current study, 26 young men were randomly assigned to one of two groups; both took part in three separate experiments: one in which they drank vodka mixed with Red Bull, another in which they had vodka mixed with fruit juice, and a third where they drank only the energy drink.

All completed three experimental sessions were seven days apart and at each session, researchers recorded the participants’ subjective sensations of intoxication, as well as objective measures of their motor coordination, breath alcohol concentration, and visual reaction time.

The researchers found that the men reported fewer headache symptoms and less weakness with the Red Bull mixture compared with the standard mixed drink.

They also thought their hand-eye coordination was sharper.

But when it came to objective tests of hand-eye coordination and reaction time to visual cues, the men performed no better.

Souza-Formigoni says that although combined ingestion decreases the sensation of tiredness and sleepiness, it does not reduce the harmful effects of alcohol on motor coordination.

In other words, the person is drunk but does not feel as drunk as he really is.

Souza-Formigoni says the second important point is that many users reported using energy drinks to reduce a not-so-pleasant taste of alcoholic beverages, which could dangerously increase the amount (as well as the speed of ingestion) of alcoholic beverages.

People need to understand that the ‘sensation’ of well-being does not necessarily mean that they are unaffected by alcohol.

Regardless of how good they may feel, they should not drink and drive.

Roseli Boerngen de Lacerda, associate professor in the department of pharmacology at the Universidade Federal do Parana, Brazil, says the study shows that the use of energy drinks might predispose people to abuse alcohol when its depressant effects - or at least the perception of such effects - are masked by them.

Both Boerngen and Souza-Formigoni believe further studies are needed to test higher doses of both alcohol and energy drinks.

The study is published in the journal Alcoholism: Clinical & Experimental Research, April 2006.