I say in my author biography that I write best with slight inebriation, but I only said that because it amuses me and fits the classic archetype of the substance-abusing artist. Sure, I sometimes sneak some rum into my Coke Zero or a few drops of cognac into my tea, but I find that on days I don't drink I can write for 15 hours a day or more. On days I DO drink I can barely put in more than a normal 8-10 hour workday. I get tired and have to sleep like a normal person. Thus, I will have the productivity of a normal person, and the long term projected income of a normal person.
Over several years, or over the course of a lifetime, regular, moderate (not even excessive) alcohol intake can seriously inhibit the quality of life, and how much one gets out of life. Even if it was one extra hour of work per day that I lost from drinking, it would be too many hours. And frankly, anything that I can do or produce under the influence I can also do without it.
(Except for maybe sex scenes and really emotional dramatic scenes that make me cry. But the alcohol makes that even WORSE sometimes!)
In my story, even though the mermaids live for hundreds of years, they still treasure every minute. They are mortal; that's what makes life special, being conscious of your own mortality and choosing to make the best of every minute. Having constant goals to work towards, and channeling one's energy towards the right outputs... unless one's goal is to meander aimlessly. Which can also be interesting, and kudos for you: but at least be aggressive about the aimless meandering! Like, be determined to meander over a certain square mileage per hour, yanno?
The crux of the matter is that we all choose what we want to do with our lives and get out of our existence. I know that what I want is crazy and amazing, and I'm not willing to sacrifice any more hours to tiredness induced by alcohol... :)