When I was studying Russian in college, my professor would always ask the class (which met first thing in the morning, five days a week) how everybody was doing (in Russian, of course). Naturally, the responses were usually "fine" or "good", because that's how people normally respond to such a question.
But since I'm 1) a smartass, and 2) a very literal person, I actually answered the question... so one of the first adjectives I learned in Russian was устал (trött i svenska).
After a couple of weeks with no sign of me ever being well-rested, my professor decided the class needed to learn как всегда. And now, relatively much later in my Swedish studies, I can answer the same question in nearly the same way in Swedish, thanks to som vanligt (and also, maybe, som alltid?)
Jag är trött, som vanligt
It's pretty common (considering that the state it denotes is so rare for some of us) but it's hard to translate into both Russian and English. I thought a little about that when I posted that comment and the best words I could think of were бодрый or энергичный, maybe живой. English is no better – perky perhaps? alert ? or again, energetic.
Although you can use "middag" to mean noon, that use is very rare and almost everyone only mean dinner (evening meal) when they say "middag". Instead, we'd say "mitt på dagen" for meaning around noon in a very general sense, or "klockan tolv" or "vid tolv" to be specific. So, your sentence would rather translate to "Som vanligt är jag hemma vid tolv" or something like that.
I'm not sure if I fully understand how to use vanligtvis/vanligen/vanligt. I believe that vanligtvis=vanligen and it's an adverb that means usually, while vanligt is an ett-word form of vanlig, so it's an adjective that can be used in a phrase "som vanligt" - which serves as a kind of an adverb. Is that correct?
"Like normal" works fine for me as a native speaker of English. Given that one other person has said it doesn't work in English, and one person has said it's "not the most natural sounding" I would have to guess there are regional differences* in its (non-)usage - it doesn't sound the least bit unnatural to me*.
Of course, the useful information (for Swedish learners) implied by the other posts is that this works in Swedish / this is what the Swedish means. [Italics to indicate my summary of what I understand their posts imply.]
[*It's possible the users who made the other posts imagined different contexts in which "like normal" is less "natural", but as this is out of context and there are contexts in which (for me) it is correct, my previous comment about this not being unnatural stands.]
Yes, it's from the adjective van ("accustomed" to), from the verb vänja (to "accustom"), which exists in forms in all Germanic languages and which was in Proto-Germanic as well. English has it as e.g. to "wean".
The ultimate root is a Proto-Indo-European verb meaning to "desire". It's the same root we have in e.g. "venison", "venereal", "win", etc.