Learn Hardcore Indonesian: Setelah lembur, dia kelelahan dan tidur lebih awal. - After working overtime, he/she was exhausted and slept earlier.

As an activity: Saya lembur tadi malam. = I worked overtime last night.
As a noun: Uang lembur = overtime pay.
You can also say kerja lembur (“work overtime”), which is more explicit but no more correct than just lembur. The sentence’s Setelah lembur is like “After working overtime.”

Rare/less common forms like berlembur exist but are not usual in casual speech.

Is there any difference between setelah and sesudah?

They’re near-synonyms meaning “after,” and are interchangeable in most contexts:

Setelah lembur, ...
Sesudah lembur, ...

Style notes:

setelah feels slightly more formal in some ears, but both are standard.
Other variants: sehabis (informal), habis (very informal), usai (formal/literary).

Why is there a comma after Setelah lembur? Is it required?

When a time clause/adverbial comes first, Indonesian typically uses a comma before the main clause:

Setelah lembur, dia ...

In informal writing you’ll sometimes see it omitted, but the comma is recommended.

Does dia mean “he” or “she”? How do I specify gender?

Dia can mean either “he” or “she.” Indonesian pronouns don’t mark gender. To be explicit, add a noun:

dia (laki-laki/pria) = he (male)
dia (perempuan/wanita) = she (female)

Other pronouns:

ia (more formal, usually as subject)
beliau (respectful, for someone you honor)

What’s the nuance difference between lelah, kelelahan, and capek?

lelah/letih: tired. Neutral.
capai/capek: tired. Very common, informal/colloquial.
kelelahan: exhausted/overly tired; a stronger state than just tired. It can also be the noun “fatigue.”

So dia kelelahan ≈ “he/she is exhausted,” stronger than dia lelah.

Is kelelahan an adjective or a noun here?

Here it functions adjectivally as a predicate (“is exhausted”): dia kelelahan. It can also be a noun:

kelelahan kronis = chronic fatigue
mengalami kelelahan = to experience fatigue

There’s no past tense marker. How do we know it’s past? How would I mark it explicitly?

Indonesian doesn’t inflect verbs for tense. Sequence words like setelah imply order, and time words handle time:

Past time markers you can add: tadi malam (last night), kemarin (yesterday), barusan/baru saja (just now), sudah/telah (already; aspectual, not strictly tense). Example: Setelah lembur tadi malam, dia kelelahan dan tidur lebih awal.

Can I say Setelah dia lembur instead of Setelah lembur?

Yes. Both are natural:

Setelah lembur, dia ... (elliptical “after working overtime”)
Setelah dia lembur, dia ... (explicit subject) You could also say Setelah bekerja lembur, ... for clarity.

Is there any difference between lembur and kerja lembur?

They mean the same in practice. Lembur by itself already implies working overtime. Kerja lembur is just more explicit. Both are common:

Saya lembur.
Saya kerja lembur.

Why is it lebih awal (“earlier”) and not lebih cepat (“faster”)?

awal relates to a point on the clock/schedule: early/earlier.
cepat relates to speed: fast/faster. So for going to bed earlier, use lebih awal (or add context: lebih awal dari biasanya = earlier than usual). Lebih cepat would mean “faster,” not “earlier,” though in casual speech you might hear imperatives like cepat tidur! (“go to bed quickly!”).

Are there other natural ways to say “sleep earlier”?

Yes:

tidur lebih awal (neutral)
tidur lebih cepat (heard in casual speech, but many prefer lebih awal for time)
Make the comparison explicit: tidur lebih awal dari biasanya (earlier than usual), tidur lebih awal dari teman-temannya (earlier than his/her friends)

Why is there no prefix on tidur? Should it be bertidur or something?

Tidur is already a complete intransitive verb (“to sleep”) and normally appears without prefixes. Related forms:

menidurkan (anak) = to put (a child) to sleep
meniduri = to sleep with someone (sexual; be careful)
tiduran = to lie down/rest (not necessarily to sleep)

Could I use lalu or kemudian instead of dan?

Yes, with slight nuance differences:

dan = and (just links two predicates)
lalu/kemudian = then/after that (emphasize sequence) Examples:
Dia kelelahan dan tidur lebih awal.
Dia kelelahan lalu/kemudian tidur lebih awal.

What’s the difference between tertidur and ketiduran compared to tidur?

tidur = to sleep (neutral).
tertidur = (to) fall asleep (often unintentionally), focusing on the moment of dozing off.
- Dia tertidur di sofa. = He fell asleep on the sofa.
ketiduran = fell asleep unintentionally and/or ended up sleeping longer than intended (accidental).
- Dia ketiduran, jadi tidak sempat makan. = He accidentally fell asleep, so he didn’t have time to eat. For “oversleep (in the morning),” a common word is kesiangan.

Does lebih awal imply “earlier than what,” or do I need to say it?

By default it means “earlier than expected/than usual” from context. You can make it explicit:

lebih awal dari biasanya = earlier than usual
lebih awal daripada rencana = earlier than planned

Any pronunciation tips for the key words?

lembur: ləm-bur (the e is a schwa, like the a in “about”)
kelelahan: kə-lə-lah-an (both e’s are schwa; stress commonly near “-lah-”)
lebih: lə-bih (final h is lightly pronounced)
awal: a-wal
tidur: ti-dur (trilled/flapped r)