Learn Hardcore Indonesian: Asal kamu tidur cukup, kamu tidak akan terlalu mengantuk di kelas. - As long as you sleep enough, you will not be too sleepy in class.

Asal kamu tidur cukup ≈ As long as you sleep enough / provided that you sleep enough.
Kalau is more general and usually means “if / when”, without strongly emphasizing the condition.
Selama means “as long as / during the time that”, focusing more on the duration of time.

You could also say:

Kalau kamu tidur cukup, kamu… – If you sleep enough, you… (quite neutral)
Selama kamu tidur cukup, kamu… – As long as (for as long a period as) you sleep enough, you…
Asal kamu tidur cukup, kamu… – As long as / provided that you sleep enough, you… (more conditional, like a requirement).

So asal here sounds like a requirement for the result to happen.

Why is it tidur cukup and not cukup tidur?

Tidur cukup is the usual way to say “sleep enough / get enough sleep”.

tidur = to sleep (verb)
cukup = enough (adverb here, modifying the verb)

So the pattern is: verb + adverb → tidur cukup (sleep sufficiently).

Cukup tidur can appear in a different structure where tidur becomes a noun:

cukup tidur = enough sleep (noun phrase: adjective + noun)
- e.g. Saya butuh cukup tidur. – I need enough sleep.

But in the original sentence we want “as long as you sleep enough” (verb phrase), so tidur cukup is more natural than cukup tidur.

Could you also say kalau kamu tidur cukup instead of asal kamu tidur cukup?

Yes, you can.

Kalau kamu tidur cukup, kamu tidak akan terlalu mengantuk di kelas.

This is perfectly grammatical and common. The nuance:

Asal → sounds a bit more like a condition or requirement.
Kalau → more neutral, “if / when”, without that strong “on condition that” feeling.

In many everyday conversations, people might naturally say kalau here.

Why is there tidak akan? What’s the function of akan in kamu tidak akan terlalu mengantuk?

Akan is a future marker, roughly like “will / going to” in English.

tidak = not
akan = will (future)
kamu tidak akan… = you will not… / you won’t…

So kamu tidak akan terlalu mengantuk = you will not be too sleepy.

Indonesian doesn’t always need a future marker, but using akan makes the future time reference clearer, especially in writing or more careful speech.

You could also say:

Asal kamu tidur cukup, kamu tidak terlalu mengantuk di kelas.
→ understood as a general truth / typical result, but tidak akan is more explicitly “in the future (in class)”.

Why is it tidak akan terlalu mengantuk, and not akan tidak terlalu mengantuk?

The normal order with adjectives and adverbs in Indonesian is:

subject + tidak + (modal) + adverb(s) + adjective / verb

Here:

kamu (subject)
tidak (negation)
akan (future marker)
terlalu (adverb “too”)
mengantuk (adjective/verb “sleepy / to feel sleepy”)

So: kamu tidak akan terlalu mengantuk.

Saying kamu akan tidak terlalu mengantuk is not ungrammatical, but it sounds awkward and much less natural. The standard pattern puts tidak right before the phrase being negated (here: akan terlalu mengantuk).

What exactly does terlalu mean here? How is it different from sangat or sekali?

Terlalu means “too (much)” in a negative / excessive sense.

terlalu mengantuk = too sleepy (more than is good/acceptable)

Compare:

sangat mengantuk = very sleepy (strong degree, but not necessarily “too much”)
mengantuk sekali = very sleepy / extremely sleepy

So:

tidak akan terlalu mengantuk = won’t be too sleepy (won’t be excessively sleepy)
tidak akan sangat mengantuk = won’t be very sleepy (just lower intensity, not about “too much”).

What is the difference between mengantuk, ngantuk, and kantuk?

They’re related words:

mengantuk – more formal/neutral; can act like a verb or adjective
- Saya mengantuk. – I’m sleepy / I feel sleepy.
ngantuk – informal/colloquial form; very common in speech
- Aku ngantuk. – I’m sleepy.
kantuk – noun meaning “sleepiness / drowsiness”
- Rasa kantuk. – a feeling of sleepiness.

In your sentence, mengantuk is standard and fits both spoken and written Indonesian. In casual chat, someone might say:

Asal kamu tidur cukup, kamu nggak bakal terlalu ngantuk di kelas. (more colloquial).

Is mengantuk an adjective or a verb here?

In practice, Indonesian doesn’t separate adjectives and stative verbs as strictly as English. Mengantuk can function both ways:

Like a verb: Saya mengantuk. – I feel sleepy / I am getting sleepy.
Like an adjective: Saya sangat mengantuk. – I’m very sleepy.

In kamu tidak akan terlalu mengantuk, it behaves like “to be sleepy”, similar to an adjective in English, but grammatically it’s still a stative verb.

Can I omit kamu in asal kamu tidur cukup and just say asal tidur cukup?

Yes, you can.

Asal tidur cukup, kamu tidak akan terlalu mengantuk di kelas.

This is natural if it’s clear from context that “sleep enough” refers to “you”. Indonesian often drops pronouns when the subject is obvious.

You could also drop the second kamu:

Asal kamu tidur cukup, tidak akan terlalu mengantuk di kelas.

Again, context tells us who will not be sleepy. In formal written Indonesian, keeping the pronouns is a bit clearer, but in speech, omission is very common.

Can the order of the two clauses be reversed? For example, can I say Kamu tidak akan terlalu mengantuk di kelas, asal kamu tidur cukup?

Yes. Both orders are fine:

Asal kamu tidur cukup, kamu tidak akan terlalu mengantuk di kelas.
Kamu tidak akan terlalu mengantuk di kelas, asal kamu tidur cukup.

The meaning is the same. The difference is just emphasis and flow:

Starting with asal… highlights the condition first.
Putting asal… at the end sounds more like adding a condition after stating the result.

Both are grammatically correct and natural.

What’s the function of di in di kelas? Could I say dalam kelas instead?

Di is a basic location preposition meaning “at / in / on”.

di kelas = in class / in the classroom / during class (when you are in class)

Dalam also means “in / inside”, but it often has a slightly more “inside / within” feeling and is more formal in many uses.

di kelas → everyday, natural: where you are (in class).
dalam kelas → can sound more formal or more literally “inside the classroom”.

In normal conversation about being sleepy in class, di kelas is definitely the most natural choice.

Is kamu always appropriate, or should I sometimes use Anda or something else?

Kamu is informal and friendly, used with:

friends
similar age / younger people
people you are close to

Other options:

Anda – polite, neutral; good for strangers, customers, formal writing
- Asal Anda tidur cukup, Anda tidak akan terlalu mengantuk di kelas.
Using the person’s name or title:
- Asal Budi tidur cukup, Budi tidak akan terlalu mengantuk di kelas.
Kalian – plural “you (all)”

So choose the pronoun based on the social situation and how formal you want to be.

Is there any difference between tidur cukup and cukup istirahat in meaning?

Yes, slight difference:

tidur cukup = sleep enough / get enough sleep (specifically about sleep)
cukup istirahat = rest enough / get enough rest (more general: could include sleeping, relaxing, taking breaks)

Both can reduce sleepiness, but tidur cukup is more directly about your sleep duration/quality, which is exactly what’s being linked to not feeling sleepy in class.

Can this sentence be understood as a general rule, or is it only about one specific future time?

It can be read both ways, depending on context:

Specific future time (e.g., tomorrow’s class)
- As long as you sleep enough (tonight), you won’t be too sleepy in class (tomorrow).
General rule / habitual
- As long as you (generally) get enough sleep, you won’t (typically) be too sleepy in class.

Indonesian doesn’t mark tense strongly, so asal + present verb + akan often feels like a general conditional rule, similar to English:

As long as you sleep enough, you won’t be too sleepy in class (in general).