According to the Yerkes-Dodson Law, there is optimal point of arousal and performance. Suppose a person takes a stimulant such as Adderall. This would increase his arousal. However, it may increase his anxiety (e.g. side effects). Would combining a downer (such as alcohol) with an upper (such as Adderall) maximize productivity? This is assuming that at a baseline level, a person cannot maximize his productivity.  
Yerkes-Dodson Law and Drugs
performance;drugs