A lot of people don't think of it from this angle. There was a period where I pulled a few days to catch up on work with very little sleep and no drinking. And the end of this period, I noticed that I felt the same being sleep deprived as I did after a heavy night of drinking. At that point, I realized that much of the feeling of hangover was likely sleep deprivation.
I was under the illusion, for most of my life, that alcohol helped with sleep, until I did some research and found out it practically does the opposite. Or honestly, listened to the book "Why do we sleep" by Matthew Walker https://www.goodreads.com/book/show/34466963-why-we-sleep. It is absolutely fascinating and worth a read/listen for anyone wondering what we know about sleep so far.
An interesting point from the book: For people that drink regularly for long stretches, they can end up with dreams literally spilling into reality because their brains never reaches deep REM due to the alcohol. It's fascinating. I've never reached that level personally. However I've heard anecdotes of people getting insanely vivid dreams after stretches of drinking.
I had a similar issue. Casual once or twice a week, turned nightly over the pandemic. I also live in a country different from my birth, though the locals still speak decent English. When the country went into lockdown (followed by curfews) I didn't leave my area to see my foreigner friends, and only saw the people in the neighborhood I live in.
I feel the pandemic revealed something in me, which was basically an underlying stressor of living in a foreign country and working from home. Previously, I was able to distract myself from the stressor with a lot of activity. I filled my days with work, being among friends, and other activities. These things were a distraction which sort of enabled me to outrun having to face this underlying issue. The pandemic slowed time down to the extent that I had to face these things head-on. Instead of dealing with them properly, I numbed myself with alcohol and a relationship which didn't have lasting fundamentals.
Towards the end of the pandemic restrictions, I had a difficult time with focus because of issues in the relationship and being hung over every morning. The switch back to "normal" was leaving me behind, because I wasn't adapting. I had built a lifestyle in which both the alcohol and the relationship were the escape, and then the relationship ended and I knew I needed to stop the alcohol.
I don't think I have gone backwards, or that alcohol has negatively affected my skills. In some ways, I feel that age helps. But I'm far behind where I would be if I didn't drink. I didn't do nearly as much work as I would have, and the work I did wasn't as high quality. Otherwise, it's hard to measure.
You may need more time to recover. To fully recover, you may need to stop completely. Though my tolerance went way up, I'll still feel horrible the next morning even with the equivalent of two beers. My greater concern right now isn't even so much the alcohol, as it's the underlying issues which sent me into the spiral in the first place. I feel that I'm working through it emotionally, so it's hard to put it into words. Maybe feeling my way out of it is the key, rather than rationalizing it. I feel I'm making progress though.
