Learn Hardcore Japanese: watasi ha hirune wo suru zikan ga hotondo nai.

Because Japanese often uses a topic–comment structure. 私は sets the topic “as for me,” and inside that, 時間が marks the grammatical subject of the predicate ない. Literally: “As for me, time (to nap) does not exist.” This is the common way to say “I don’t have X” in Japanese: Topic + Xが + ある/ない.

Why is it 時間が and not 時間は?

時間がほとんどない states the simple fact that there is (almost) no time.
時間はほとんどない topicalizes “time” and often implies contrast (e.g., “As for time to nap, there’s almost none, though [something else] might be different”). Use が for neutral existence/possession; use は when you want to contrast or highlight that specific noun.

What does 昼寝をする時間 mean grammatically?

It’s a relative clause: 昼寝をする (to take a nap) modifies 時間 (time), forming “time to take a nap.” Japanese doesn’t use relative pronouns; the verb phrase directly precedes the noun it modifies.

Do I have to include を in 昼寝をする時間? Can I say 昼寝する時間?

Both are correct. With many する-verbs:

昼寝をする時間 and 昼寝する時間 are both natural. Dropping を is common and slightly leaner. Keeping を can feel a touch more explicit/formal.

Why is the verb before 時間 in dictionary form?

When a verb phrase modifies a noun (a relative clause), Japanese uses the plain dictionary form. So it’s [V-dictionary] + 時間 = “time to [do V].” Example: 勉強する時間 (time to study), 食べる時間 (time to eat).

Could I say 昼寝の時間がほとんどない instead?

You can, but it changes nuance:

昼寝をする時間 = “time to take a nap” (any available time in your schedule).
昼寝の時間 = “nap time” as a designated period (like a scheduled slot). The original sentence focuses on available time, so …をする時間 is more natural.

What exactly does ほとんど mean here?

Here ほとんど pairs with a negative to mean “almost” in the sense of “hardly/virtually none.” Common pattern: ほとんど + [negative predicate] = “hardly/rarely/almost no …”

ほとんどない = there is almost none. Positive uses exist too, like ほとんどの人 (“most people”).

Can I use あまり instead of ほとんど?

Yes, but nuance differs:

あまり時間がない = not much time (there is some, but not a lot).
時間がほとんどない = almost no time (stronger). So ほとんど is a stronger “nearly zero” than あまり.

Is this about not napping often, or not having time to nap?

This sentence is about time availability: 昼寝をする時間 (time to nap). If you want “I hardly ever nap,” say:

私は昼寝をほとんどしない。 That targets frequency of the action, not the time resource.

Why is there no です at the end? How would I make it polite?

The sentence is in plain form. Polite versions:

私は昼寝をする時間がほとんどありません。 (most standard)
…ほとんどないです。 is also widely used in conversation.

Past polite: …ほとんどありませんでした。

Can I omit 私は?

Yes. If context already makes it clear you’re talking about yourself, just say:

昼寝をする時間がほとんどない。 Japanese frequently omits pronouns when they’re understood.

Can I change the word order?

Within limits, yes. Natural variants include:

私は昼寝する時間がほとんどない。 (drop を)
昼寝する時間はほとんどない。 (contrastive topic on 時間)
ほとんど昼寝する時間がない。 (moving ほとんど earlier for emphasis) Avoid splitting the relative clause in awkward ways; keep [昼寝(を)する] together before 時間.

Why not use 持つ for “have,” like 時間を持っていない?

For “having time/money/siblings/etc.,” Japanese typically uses Xがある/ない with the possessor as topic: 私は時間がない. 持つ is for physically holding/owning tangible items and is unnatural with 時間 in this sense.

What’s the difference between 時間 and とき here?

時間 = an amount/availability of time.
とき（時） = a time/when (a point or occasion). You need 時間 for “time (available) to do something.”

Could I use 暇 (ひま) instead of 時間?

Yes, with a nuance shift:

昼寝する暇がない = no free time/leisure to nap (focus on free time).
昼寝する時間がない = no time (schedule/availability) to nap (neutral). Both are common; 暇 can imply “no spare time.”

What exactly is 昼寝? Is it only at noon?

昼寝 means a daytime nap (any time during the day). お昼寝 is a softer/polite form, often used with/for children. It’s not restricted to exactly noon.

Is が marking the subject of ない?

Yes. In [昼寝をする]時間がほとんどない, the subject of ない is 時間. The larger topic 私 is introduced by は and is not the grammatical subject of ない.

How would I make the statement stronger or softer?

Stronger (virtually zero): 昼寝する時間が全然ない。 (very emphatic)
Softer (not much): 昼寝する時間があまりない。
Formal stronger emphasis: ほとんどありません or ほとんどございません (very formal).

Any quick pronunciation tips?

Natural chunking is:

わたしは｜ひるねをする｜じかんが｜ほとんどない。 Try to keep 昼寝をする together as one modifier of 時間 when speaking.