I found this very interesting USA Today article and thought it was worth sharing. I travel a fair amount on aircraft and I find it interesting to see how quickly people who order a cocktail or two get a bit tipsy. This is a good explanation of what is going on with their bodies.
While on a flight, if you've only had a couple drinks and already you're trying to convince your neighbor there's a monster on the wing, you might not be entirely crazy - it might just be that the booze has gone to your head a little more than usual.
While scientific studies have shown that drinking alcohol at a higher altitude does not actually increase your blood alcohol level, it might make you feel more drunk than usual. Suddenly after going up to 8,000 to 10,000 feet increases dizziness; lightheadedness and drowsiness, which are the symptoms of altitude sickness. These are also sensations associated with being drunk (in case you can't recall). So, altitude + alcohol = dizzy times two.
Read More at http://roadwarriorvoices.com/2015/08/17/what-alcohol-really-does-to-your-body-on-an-airplane/