Learn Hardcore Japanese: narubeku hayaku nereba, asa ha okirareru hazu da. - If I go to bed as early as possible, I should be able to wake up in the morning.

It means "as much/as ~ as possible," and here it makes the set phrase なるべく早く "as early as possible." できるだけ is a near-synonym (slightly more common/neutral). なるだけ/なるたけ are casual variants. All work in this sentence: なるべく/できるだけ早く寝れば….

Why is 早く used instead of 早い?

早い is an adjective; 早く is its adverb form, which modifies verbs. Since 寝る is a verb, you need 早く寝る "to go to bed early." 早い寝る is ungrammatical.

What does the conditional 寝れば express? How is it different from 寝たら, 寝ると, or 寝るなら?

〜れば: hypothetical "if … then …"; fits a reason-result statement.
〜たら: "when/if (and then)"; more eventy/colloquial; also fine here.
〜と: automatic/habitual result; sounds like a rule of thumb.
〜なら: assumption/topic-based "if it’s the case that …"; often used in response to context. Negative note: 早く寝なければ、朝は起きられない means "If you don’t go to bed early, you won’t be able to get up."

Does 寝れば mean "you should sleep early" (advice)?

No. 寝れば is a condition ("if you sleep/go to bed"). For advice, use なるべく早く寝たほうがいい or (stronger) 早く寝るべきだ.

Why is there a comma after 寝れば?

It simply separates the conditional clause from the main clause. It’s optional: なるべく早く寝れば朝は起きられるはずだ is fine.

What is the role of 朝は? Why は instead of に?

朝は marks "morning" as the topic ("as for the morning"), often with a contrastive feel ("at least in the morning"). 朝に marks a time point and is less natural for a general ability/expectation with はずだ. 朝には起きられる means "be able to get up by morning." You can also just say 朝、起きられる in conversation.

Is 起きられる a potential or a passive form?

Potential: "can wake up / be able to get up." For ichidan verbs like 起きる, 〜られる can be either passive or potential; context tells you which. Here there’s no agent and a passive reading would be odd, so it’s potential.

Can I say 起きれる instead of 起きられる?

You’ll hear it in casual speech (ら抜き言葉), but it’s still considered nonstandard in careful writing and on tests. Prefer 起きられる.

What exactly does はずだ mean here?

はずだ expresses a logical expectation based on known reasons/facts—"should (be the case)" in the sense of "it stands to reason that...," not obligation.

How does はずだ compare with でしょう or と思う?

はずだ: reasoned expectation; relatively confident.
でしょう: conjecture/guess; softer, polite-sounding.
と思う: personal opinion/belief; softer and subjective. So 起きられるはずだ is stronger/more reasoned than 起きられるでしょう or 起きられると思う.

How do I make the sentence polite?

Use です at the end: なるべく早く寝れば、朝は起きられるはずです。 You can soften further with と思います: …起きられるはずだと思います。

Who is the subject here?

It’s omitted; context decides. It could be "I," "you," or "we." To make it explicit: 私がなるべく早く寝れば、朝は起きられるはずだ。 / 君が….

Could I use できる to express ability instead of the potential form?

You can say 朝は起きることができるはずだ, but it’s wordier and sounds more formal. With intransitive verbs like 起きる, the potential form 起きられる is preferred.

Is 速く okay instead of 早く?

No. 早い/早く = early (time); 速い/速く = fast (speed). 早く寝る = go to bed early. To say "fall asleep quickly," use different wording, e.g., すぐ寝つく or すぐ眠れる.

Why isn’t there a が after 起きられる? I thought abilities use が.

That change (を → が) applies to potential forms of transitive verbs (e.g., 漢字が読める). 起きる is intransitive, so there’s no object to mark; just 起きられる.

Can I drop the final だ?

Yes, in casual speech: …起きられるはず。 In polite speech, keep です: …はずです。

Is 寝る interchangeable with 眠る here?

Prefer 寝る for "go to bed/turn in." 眠る is "to sleep (be asleep)" and sounds less idiomatic in this advice-like sentence. 早く寝る is the natural choice.

Can I reorder the elements, like putting 朝は first?

You can say 朝は、なるべく早く寝れば起きられるはずだ。 It’s grammatical, but fronting 朝は can momentarily suggest it modifies 寝れば ("sleep in the morning"). The original order is clearer.

How would I express the negative or a stronger denial?

Negative expectation: なるべく早く寝なければ、朝は起きられないはずだ。
Strong denial: 朝は起きられるはずがない。 ("There’s no way [you] can get up in the morning.")

What about using 早めに?

早めに = "on the early side/earlier than usual." It’s weaker than "as early as possible."

なるべく早く寝れば… as early as you can.
早めに寝れば… if you go to bed a bit earlier (than usual)…

Why is there no particle after なるべく早く?

Adverbs/adverbial phrases typically don’t take particles when modifying verbs. なるべく早く directly modifies 寝れば/寝る.

Is there any difference between 起きる and 起き上がる here?

起きる = wake up/get up (general). 起き上がる = physically sit/stand up from lying down. For mornings, 起きる is standard.