I am translating this sentence, and I've had a few tips from local spertulos, but see what you make of it:

"Feeling sleepy? That's the cold that does that. Confuses you, you can't think straight."

My first pass was this:
1. "Ĉu vi sentas dormeman? La malvarmeco igas tion. Malrapidigas onin, konfuzigas."

Second, after some consultation, was this:
2. "Ĉu vi estas dormemaj? La malvarmeco igas dormemecon, malviglecon, kaj konfuzon."

Since then I've had three other proposals:

3. "La malvarmeco estigas dormemecon, malviglecon, kaj konfuzon.
4. "La malvarmeco donas (al vi) dormemecon, malviglecon kaj konfuzon."
5. "La malvarmeco igas vin dormema, malvigla kaj konfuzita."

Which do you like best, i.e. is clearest? Can 'kaŭzi' be used here? Seems like it would be good for this sentence. e.g. 6. "La malvarmeco kaŭzas dormemecon, malviglecon, kaj konfuzon."

This will be in a book, so you needn't propose your own sentence.

"dormemo" is perfectly fine, the -ec- is superfluous in that case.

The -ec- is also optional in your "malvigleco" but it's also ok with it.

The English is in a much more informal conversational style, and I'm wondering why you didn't carry that into the Esperanto.

"Ĉu dormema? La malvarmo faras tion. Ĝi konfuzas, oni ne bone pensas"

erinja:The English is in a much more informal conversational style, and I'm wondering why you didn't carry that into the Esperanto.

"Ĉu dormema? La malvarmo faras tion. Ĝi konfuzas, oni ne bone pensas"

Thanks for this. I'm not sure why I didn't go for a more conversational style. I can tell you that I have been overthinking the translation of this one particular bit, maybe that has something to do with it!

With the 'ĝi' in your sentence, is there any confusion (gramatically) about whether it refers to the 'marvarmo' or the 'tion' (dormemo)? I'm wondering about the use of ĝi in a situation like this.

"Ĝi" wouldn't refer back to "dormema", because it's a pronoun, so it can only refer back to a noun. "Tio" is used to refer back to a verb, a phrase, a situation, something that is not just a single noun. So "tio" and "ĝi" have different purposes. In some old Esperanto texts you do see "ĝi" used to refer to things other than a noun, you see it referring to phrases and situations, but we don't really do that anymore today, "tio" is used for that instead. A small digression - from time to time on this forum, someone posts and they say that they want to write something in Esperanto that looks really "old-fashioned" or somewhat archaic, the Esperanto equivalent of writing in King James English, for example. Esperanto hasn't changed enough that anything looks really archaic but using "ĝi" in places where "tio" would be expected does pretty much scream out "early Esperanto" to me.

Ĝi would never refer to "tion", it wouldn't really make sense, because "ĝi" and "tio" are both ways of referring back to something else that isn't being named explicitly, for one reason or another. I've never seen it that one of these words is used to refer to another one, it would make the whole meaning incredibly unclear, you'd have to go leapfrogging back to figure out what the original concept was that you were referring to.