Although energy drinks may enhance athlete's performance they also cause insomnia and nervousness a study said. The study carried out by experts from the Camilo Jose Cela University (UCJC) Spain evaluated the positive and negative effects of energy drinks on athletes. 'Athletes felt they had more strength power and resistance with the energy drink than with the placebo drink' said Juan Del Coso Garrigas in-charge of the Exercise Physiology Laboratory at UCJC. 'However the energy drinks increased the frequency of insomnia nervousness and the level of stimulation in the hours following the competition' Juan Del Coso added. For the study