In this answer, soberity is defined as:
the condition of not having any measurable levels, or effects from
mood-altering drugs especially alcohol.
It seems that mixing stimulants with alcohol has a masking effect:
Stimulants & Alcohol: A MASKING EFFECT When you mix alcohol with
stimulants, the stimulants mask the effects of how your body is
experiencing the alcohol. Depending on how much is consumed, over the
course of however many hours, your Blood Alcohol Levels may feel
inaccurate due to the fact the stimulants are interrupting the body’s
natural ability to process the alcohol and send you the appropriate
In a post, the National Council on Alcoholism and Drug Dependence has announced that mixing energy drinks (stimulants with a lot of caffeine) with alcohol (depressant) can lead to “wide-awake drunkenness,” where caffeine masks the feeling of drunkenness but does not decrease actual alcohol-related impairment.
And as you already know caffeine is stimulant.
Therefore, caffeine masks the feeling of drunkenness but does not decrease the actual alcohol-related impairment.
Still not convinced?
In 2009, someone wanted to study the effects of drinking caffeine after alcohol. Mice were given alcohol followed by the human equivalent of 8 cups of coffee. After the caffeine they seemed more alert, but they were still much worse than sober mice at getting round a maze.
Still skeptical because it is study about rats not humans, right?
So, it is true that caffeine takes away some of that fatigue when you are sober. To show that you might believe you’re sober when you’re not, NIH studied American college students from 2008. They found out that those who chose drinks containing both alcohol and caffeine, aka energy drinks, were twice as likely to get hurt in an accident and more than twice as likely to accept a lift with a driver who was over the limit. This effect was independent of the amount of alcohol consumed. This is an early study on the topic in which the students choose their own drinks and reported themselves how much they’d drunk.
It does illustrate how caffeine could fool people into thinking they're sobering up, and some of the potentially disastrous consequences.
So far, I have showed that caffeine won't make you sober, what about any other activity such as exercise?
The answer is also no!
Your body takes a certain amount of time to metabolize alcohol. The time required (on average one hour) is dependent on the quantity of alcohol dehydrogenase, a famous enzyme, that is present. You cannot make this enzyme more abundant or more effective by drinking coffee, exercising or praying to any flying spaghetti monster; it won't speed up the process. More information and evidence in the post.