In a paper called "Creativity on tap? Effects of alcohol intoxication on creative cognition" by Dr. Mathias Benedek the authors examined creativity-measuring tasks in 89 volunteers after drinking beer. The article was published in the Journal of Conscious Cognition in July 2017.
The participants were either given an alcoholic or non-alcohol beer and each participant from the alcoholic-beer group had to reach the level of mild intoxication of 30mg of alcohol in every 100ml of blood (half the English drink driving limit). A total of 70 young adults (54 % female), aged between 19 and 32 years (M = 23.3; SD = 2.8), finally participated and completed all measures.
After becoming intoxicated they then had to complete a word association task, a creative thinking task, having to come up with as many creative uses as they could for common objects. On both these tasks, the alcohol beer group performed better.
The study also found that alcohol reduces ‘cognitive control’, which can be a hurdle in solving creative tasks. When someone has creative block or a so called "fixation effect", alcohol may play a role in reducing it and helps people to "think out of the box". Dr. Benedek says "In creative problem solving, problems can often only be solved after a restructuring of the problem representation. When initial solution attempts get on the wrong track, this can cause blocks to immediate problem solving, which is known as mental fixation. Alcohol may reduce fixation effects by loosening the focus of attention."
However, while alcohol boosted creativity it decreased ‘executive function’ and so is likely to impede artistic endeavors which require motor skills, such as playing the piano or dancing.
The paper says (in a very technical way):
"Creative cognition is assumed to rely on both controlled, goal-directed and spontaneous, undirected cognitive processes. Pertinent research mostly focused on divergent thinking (viz. creative idea generation) and creative problem solving (i.e., problems that can be solved either analytically or insightfully, which typically implies a restructuring of the problem representation). The relevance of cognitive control for divergent thinking is evidenced by consistent correlations with intelligence, particularly with fluid intelligence and broad retrieval ability. . At the level of executive abilities, divergent thinking has been associated with working memory capacity and cognitive inhibition. Divergent thinking requires overcoming prepotent, uncreative response tendencies and involves cognitive strategies, which was shown to be facilitated by intelligence. While much of the empirical evidence on creative cognition and cognitive control is based on divergent thinking, similar evidence also exists for creative problem solving. Creative problem solving tasks like Duncker’s candle problem or the Remote Associates Test can be achieved in a strategic way and higher performance again has been related to intelligence and executive control.
Creativity has also been associated with disinhibition and spontaneous insight. Empirical evidence for the relevance of spontaneous, undirected cognitive processes in creative thought mostly comes from research on incubation processes. Creative problem solving sometimes leads to an impasse of thought, also known as mental fixation, were goal-directed solving attempts are no longer fruitful. Incubation research has demonstrated that breaks from deliberate problem solving can benefit creativity by refreshing inadequate mindsets while leaving room for unconscious work. Similarly, while expertise typically supports problem solving by guiding search through problem space, it can also be detrimental when misdirecting search efforts to salient but inadequate concepts. Together, these findings suggest that cognitive control generally supports creative cognition by facilitating the effective implementation of goal-directed processes, but focused attention may sometimes be ineffective and potentially even harm creative problem solving.