Hey, I was shit tired as I went out to meditate today. I lied down, had a couple of beers beforehand, and intuitively tried to align myself by just letting be. I went into a state similar to unconsciousness, but subtly aware.
It has happened several times before and it is deeply rejuvenating. Before the meditation I felt broken, very tired and in a craving-monkey state of mind. Afterwards I was calm and relaxed.

Could anyone explain it to me? As I get "back into life" I am unsure if I was sleeping or not, but while I am in that state it feels as though I am deeply relaxing and shutting off unneccesary conscious activities. Reminds me a bit of sleep hypnagogia without all the hallucinations and fear.

Also, lately, during sleep I feel as though I am half-awake. This started a few months ago and I've been approximately meditating 1.5 hours daily for the last two years. Not sure if my sleep quality is poor or if I am becoming more aware in the sleeping state.

?

Not sure about your second question but this is a fairly comprehensive review about the pharmacology of alcholol:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC165791/

I can't drink because even one beer gives me insomnia and the muddleheadedness from the insomnia is worse than the effects of alcohol.

So if you are not sleeping well it might be from the beers.

You might like this kind of meditation it is better than beers or drugs.
https://sites.google.com/site/chs4o8pt/meditation-1#meditation_serenity

It's like this:
http://ncu9nc.blogspot.com/2015/02/joy-during-meditation.html#joy_trip

Apnea ?

I should've not mentiones the beers. This has happened before without alcohol in my system. 

Anyone?

When I’m too tired to concentrate during meditation, I sometimes just rest in a state that doesn’t seem to do much for insight but which does seem to be healing. It seems to contribute to purification, as tensions are relieved and the body seems to breath out toxins, and afterwards I’m relaxed and more clear.

Nothing surprising really. It is possible to remain aware during all four phases of sleep: Hypnagogia, hypnopomp, REM, and deep / dreamless sleep. From what you write, it is possible that it was a hypnopompic state.

Equating sleep with unconsciousness is a common misunderstanding which is, sadly, reinforced by some meditation teachers.

Awareness during the different phases of sleep may or may not affect the quality of sleep, depending a lot on the specifics. Once I did the experiment to basically lock myself up in the hypnagogic state for what I guess was a few hours (hard to tell, as you can imagine), and it fucked up the following four or five days of the retreat. But if you do nothing extreme like that, the quality of sleep is usually unaffected.

That's, of course, excluding medical conditions and so on.