space out and la-la land

Reader's Digest１０月号悩み相談のコーナーに "I have trouble concentrating." と言う方からの投書からです。
I sometimes space out and can't remember big chunks of the trip. My head's always wandering into la-la land.
"space out" はいかにも考えていることとか気持ちがどっかにも飛んでいってしまう感じで "la-la land" も夢の世界の様ですがどうでしょうか？　辞書で確かめます。
まず "space out" :
Dictionary.com: Stupefy or disorient, as if or from a drug. For example, This medication spaces me out so I can't think clearly, or I wonder what those kids are onthey look totally spaced out.
Wiktionary: To stupefy, intoxicate, disorient, or lose attention or focus, especially by the use of drugs.
It is easy to daydream (i.e. space out) when you try to read anything uninteresting, so this often does not bode well for college students who need to read large sections of insipid textbooks as part of a required assignment.
飛んでいってしまうより、もうろうとなり、ボーっとした状態になるようですね。
"la-la land" はどうでしょう。
OneLook Quick Definitions:　A state of mind characterized by unrealistic expectations or a lack of seriousness.
American Herritage Dictionary:　A state of being out of touch with reality, as in I don't know what's going on with Amy she seems to be in la-la land.
１年ちょっと前に書いた "cloud-cuckoo land" や　"never-never land" などと似たような言葉ですね。.