I realized I only ever dream in my native language (English). I never dream in any of the languages I've studied.

Sure, I dream in Japanese. I had a really stupid dream last night where I was in Thailand or somewhere but managed to get by speaking Japanese because no one understood English.
I don't think there's much significance to dreaming in Japanese or not though. You probably will at some point seeing it's a significant part of your waking life and all, but I don't think it's any big milestone or anything.

I read a book on dreams years ago that said you don't actually dream in words. That is, once in a while, you'll have a word or two pop up, but as far as actually "thinking out loud" while you sleep, it doesn't happen.

According to the book, you may imagine you're having a conversation, but if you try to recall exactly what was said, you can't. So, in a sense, you're only dreaming that you're dreaming in Japanese.

I don't know what anyone else's experience is, but I don't personally dream in words. Once in a while I'll wake up and utter something, and usually that's in Japanese, but that's as far as it goes.

If you live in Japan for a while you'll probably start dreaming in Japanese. I disagree with JapaneseRuleOf7 on this a bit, though. While it's probably true about 80% of the time, very often I'm constructing sentences in my head the same way I do when I'm having a Japanese conversation when I'm awake. So I usually remember a few of the sentences that I said in my dream.

However, I usually don't remember the Japanese words for what the person I'm speaking to said.

I dream in English and Japanese. Sometimes both.
On a related(?) note, I also sometimes remember conversations in a different language than what they actually were. For example- I have a conversation on Skype with my mother and later remember that conversation in Japanese. My mother does not speak Japanese. It's a strange thing.

i do dream in japanese, at least, the little amount of japanese i know. when i was learning hirigana, i would dream about the hirigana in my head. and japanese phrases come out of nowhere in my dreams.

I've found that my dreams carry the idea of words and conversation, but it's only understood to be in English or Japanese, but not in either. Maybe the occasional word pops up if I've been really focused on it, but it's kind of like your own internal monologue: when you aren't actively thinking of words, your brain merely suggests them, save for a few here or there, it's far quicker to just think the concepts than to dig for the words.
I think this is related to the situation drdunlap mentions about remembering conversations being in the wrong language: most of the actual words are forgotten and only the idea of the conversation remains; if you're in a Japanese state of mind, you might reconstruct the ideas with Japanese instead of the original English.

Granted, my formal knowledge of the brain is limited, so I don't know if anything I've written is accurate, however, with the experience I have with lucid dreaming, I at least know that I don't usually use words in my dreams, just the concepts they represent (actually, paying attention to what you're saying is a good tool to use for realizing you're dreaming, since it activates parts of your brain that participate in active thought; furthermore, trying to listen to yourself (or anything) will yield muffled and distorted sounds, since your brain is only using the idea of sound while possibly incorporating sounds from the real world; in other words, there's no real sound, so when you try to think about it, you realize that it's impossible for it to sound that way in the situation and you start to wake up).

Dreams are just constructs of ideas; since none of it is actually real, you're not dreaming in the language, but dreaming the idea of the language; that doesn't mean things you've been studying don't show up (on the contrary, they're more likely to), but if you tried to interpret it, it'd be nonsense, you have to be awake to use language.

While living in Argentina and studying intensely at language school, after a few months I began to dream in Spanish.

At first the "conversations" were incredibly slow as I kept searching for vocabulary, then correcting the grammar. Over and over again for the same sentence.

One might speculate the dreams were part of the brain organizing the language. Maybe I was not dreaming at all but consciously trying to make a story in my head before sleeping. Maybe they were "active" study sessions. We can debate quite a while on the science behind dreams.

Regardless, those months were very special as my language skills ramped up quickly. That was the point of critical mass - not sure if the dreams had anything to to with the change or were just a consequence. Eventually I reached near native fluency in Spanish.

Haven't quite had that epiphany in Japanese (yet).

I don't remember the content, but I dreamed last night that I was talking to 浜崎あゆみ, she is japanese so I figure we could only be talking in japanese.

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[Zgarbas]

I don't really remember my dreams but when I do they're in English or (oddly enough) Spanish. I think.

I remember the first time I dreamt in Japanese though; it was right before my first Kanji test and I'd spent like 10 hours straight cramming, and the 2-3 hours of sleep I got before the exam were all kanji textbook. It was amazing.

I don't dream very often these days (or rather, I don't remember them very often these days) but I had a bilingual dream last night that was fun.

I was in the beer bar in Osaka where I used to work and I was talking to everyone in English. They were incredibly confused and all responded in Japanese.. but no one thought to stop and ask my why I was speaking English. Orders piled up more and more and I could barely keep up as I was attempting to work in a busy environment in a language no one understood. Halfway through the dream it clicked- "Oh, this is Japan!" and I switched to Japanese. No one thought this was odd and work went on as usual-- only much smoother this time.

Oh, dreams.

Zgarbas Wrote:I don't really remember my dreams but when I do they're in English or (oddly enough) Spanish. I think.

I remember the first time I dreamt in Japanese though; it was right before my first Kanji test and I'd spent like 10 hours straight cramming, and the 2-3 hours of sleep I got before the exam were all kanji textbook. It was amazing.

I had an experience like this once. I think it was during the summer where I crammed four novels despite never having read a novel before. I guess when we overdo it our brains just keep on working long after we give up.