Learn Hardcore Indonesian: Adik saya mengantuk setelah menonton film di malam hari. - My younger sibling is sleepy after watching a movie at night.

adik = younger sibling (brother or sister)
In some contexts, adults may call a younger person adik as a friendly or polite form of address, like “kid” / “younger one”.

In this sentence, adik saya clearly means my younger sibling.

Why is saya placed after adik? Why not saya adik?

In Indonesian, possessive pronouns usually come after the noun:

adik saya = my younger sibling
rumah saya = my house
teman saya = my friend

If you say saya adik, that is a different structure:

saya = I
adik = younger sibling

saya adik would be understood as “I am the younger sibling” (usually with some extra context), not “my younger sibling.” So adik saya is the correct order for “my younger sibling.”

Does adik saya mean “my younger brother” or “my younger sister”?

Adik is gender‑neutral. It just means “younger sibling.”

If you want to be explicit:

adik laki-laki = younger brother
adik perempuan = younger sister

So:

adik laki-laki saya = my younger brother
adik perempuan saya = my younger sister

In everyday speech, people often just say adik saya, and the gender is clear from context.

Is mengantuk a verb or an adjective? Why is it used instead of “is sleepy”?

Mengantuk behaves like a stative verb: it describes a state, similar to “to be sleepy” or “to feel sleepy.”

Adik saya mengantuk
Literally: “My younger sibling is sleepy / feels sleepy.”

Indonesian doesn’t need a separate word like “is” here. The verb mengantuk already carries the meaning of “to be in a sleepy state,” so you just say adik saya mengantuk, not adik saya adalah mengantuk.

What’s the difference between kantuk, mengantuk, and ngantuk?

They’re related but used differently:

kantuk – noun: “sleepiness, drowsiness”
- Saya merasa kantuk. = I feel sleepiness / I feel drowsy.
mengantuk – stative verb: “to be sleepy / to feel sleepy”
- Saya mengantuk. = I am sleepy.
ngantuk – informal / colloquial form of mengantuk
- Saya ngantuk. = I’m sleepy. (very casual speech)

In your sentence, mengantuk is a neutral, standard form suitable for both spoken and written Indonesian.

In setelah menonton film, who is doing the watching? Why is there no subject?

The subject of menonton is understood to be the same as the subject of the main clause, namely adik saya.

So:

Adik saya mengantuk setelah menonton film di malam hari.
= My younger sibling is sleepy after (they) watched a movie at night.

Indonesian often drops the subject in a subordinate clause when it’s the same as the main subject.

If the subject were different, you would normally mention it:

Setelah saya menonton film, adik saya mengantuk.
After I watched a movie, my younger sibling was sleepy.
Setelah adik saya menonton film, dia mengantuk.
After my younger sibling watched a movie, they were sleepy.

Can I use sesudah instead of setelah here? Is there any difference?

Yes, you can. Setelah and sesudah both mean “after” and are almost always interchangeable.

Adik saya mengantuk setelah menonton film di malam hari.
Adik saya mengantuk sesudah menonton film di malam hari.

Both are correct. Nuance:

setelah is slightly more common in everyday use.
sesudah can feel a bit more formal or old‑fashioned in some contexts, but it’s still normal and correct.

Why is di used with malam hari? I thought di was only for place, not time.

Traditionally:

di is mainly for location: di rumah (at home), di sekolah (at school).
For time, many style guides prefer pada: pada malam hari (at night).

However, in real everyday Indonesian, di is very commonly used before time expressions too:

di malam hari, di pagi hari, di siang hari, di sore hari, etc.

So:

pada malam hari = more formal / textbook
di malam hari = very common in speech and informal writing, and widely accepted.

Is di malam hari the only way to say “at night”? What about malam hari or just malam?

You have several natural options, with small differences in style:

di malam hari – at night (neutral, common)
pada malam hari – at night (more formal)
malam hari – at night (no preposition, also fine)
pada malam – at night (formal, slightly shorter)
malam – at night (very simple: Adik saya mengantuk setelah menonton film malam.)
malam-malam – at night / late at night (colloquial, gives a more casual feel)

So the sentence could also be:

Adik saya mengantuk setelah menonton film malam hari.
Adik saya mengantuk setelah menonton film pada malam hari.

They all convey essentially the same time frame.

There is no word for “a” or “the” before film. How do you know if it’s “a movie” or “the movie”?

Indonesian does not have articles like “a/an” or “the.” A bare noun like film can be:

“a movie,” “movies,” or “the movie” depending on context.

If you really want to show indefinite, singular (“a movie”), you can add a classifier:

sebuah film = a movie (one movie, unspecified)

If you want it to be clearly definite (“the movie / that movie”), you often add itu:

film itu = that film / the film

In your sentence:

setelah menonton film di malam hari
is naturally understood as “after watching a movie at night” unless the context clearly points to a specific movie.

How do we know this happened in the past? There’s no past tense in the sentence.

Indonesian verbs do not change form for past, present, or future tense. Time is usually understood from:

time words: tadi malam (last night), kemarin (yesterday), besok (tomorrow), etc.
context and logic: setelah (“after”) + an action implies a sequence in time.

In:

Adik saya mengantuk setelah menonton film di malam hari.

The combination of setelah (“after”) and malam hari (“at night”) plus real‑world logic makes it natural to interpret the watching as already done and the sleepiness as a result, so English translates it with a past meaning.

To make it explicitly past, you could add a time word:

Adik saya mengantuk tadi malam setelah menonton film.
My younger sibling was sleepy last night after watching a movie.

Can I change the order to Adik saya mengantuk di malam hari setelah menonton film?

Yes, that order is also grammatical:

Adik saya mengantuk setelah menonton film di malam hari.
(focus more on the whole event “after watching a movie at night”)
Adik saya mengantuk di malam hari setelah menonton film.
(slightly more focus on “at night” as the time when they’re sleepy)

In practice, both sentences will be understood the same way. Indonesian word order is quite flexible, especially with time and place expressions.

Can I say adikku instead of adik saya? What’s the difference?

Yes, you can:

adik saya = my younger sibling
adikku = my younger sibling (using the possessive suffix -ku)

Difference in nuance:

adik saya – more neutral or slightly formal, suitable in writing, polite speech.
adikku – more informal / personal, common in casual speech and informal writing, or when expressing affection/close relationship.

So you could say:

Adikku mengantuk setelah menonton film di malam hari.
which has basically the same meaning, but sounds a bit more intimate or casual.