Here is how I think about it: your cognitive processes are accustomed to certain biochemical biases. You’ve grown and developed your brain in response to stimuli under a certain set of conditions.
One set might be jacked adrenals due to your propensity for epic soundtracks and caffeine or chocolate consumption.
Another set might be alcohol and social feedback.
If you spend a lot of time in these states, your unbiased function diminishes because you are optimizing for a different chemical bias.
If you are not so far gone, or are exceptionally motivated or introspective, you can integrate those experiences, and it might expand your awareness. If you can’t, or don’t, it might increase your function while using but reduce your sober function. This effect will increase as you spend more and more time ‘high’: you are transitioning function within your own constrained cognitive capacity to a different bias.