Learn Hardcore Japanese: kintyousita toki ni sinkokyuu wo suru to, sutoresu no yobou ni mo natte sukosi otitukimasu. - When I take a deep breath when I’m nervous, it helps prevent stress and calms me a little.

緊張するとき: focuses on the state or situation of being nervous in general.
- “When I am (the kind of person who) gets nervous / in situations where I tend to get nervous.”
緊張したとき: describes the moment after nervousness has already arisen — “when I have become nervous,” “once I’m nervous.”
- It’s like saying “When I’ve gotten nervous, (then I do X).”

In this sentence, the idea is: once you’re already feeling nervous, if you do deep breathing, it helps. That “once X has happened” feeling is why the past form した is natural here.

You could say 緊張するときに深呼吸をすると…, and it would still be understandable, but the nuance shifts a little more toward “in situations where I get nervous, if I do deep breathing…” rather than “once I’ve actually become nervous…”.

What exactly does ときに do here? Why do we need the particle に after とき?

とき (時) means “time / when,” and it usually acts like a noun: “(the) time when…”.

緊張したとき = “the time when (I) got nervous”
When you want to say “at that time / when that happens,” you often add に:
- 〜ときに = “at the time when … / when …”

So:

緊張したときに
literally: “at the time (when I have become nervous)”
naturally: “when I get nervous”

You can sometimes drop に and just say 〜とき (especially in casual speech), and many learners first see 〜とき without に.

Here, に makes it clear that the rest of the sentence (doing deep breathing) happens at that time – i.e., when you are already nervous.

Why is it 深呼吸をする and not just 深呼吸する or 深呼吸 by itself?

深呼吸 (しんこきゅう) is a noun meaning “deep breathing.”
To make it into “to take a deep breath / to do deep breathing,” you usually do one of these:

深呼吸をする
- Noun + をする is a very common pattern to turn a noun into a verb:
- 勉強をする (to study), 運動をする (to exercise), 掃除をする (to clean), etc.
- Very neutral and standard.
深呼吸する
- This is the more compact form (noun directly + する) and is also common, especially in writing or slightly more formal style titles, instructions, etc.
- In everyday talk, both forms are fine.
深呼吸 alone
- Just the noun “deep breathing.” You would need a verb around it to say what you do with it.

So 深呼吸をする here simply means “to do deep breathing / to take deep breaths.”
You could rewrite the sentence as:

緊張したときに深呼吸すると…

and it would still be good natural Japanese.

What does the と after 深呼吸をする mean? How is this different from たら or ば conditionals?

The と here is the conditional と, which often means “when/whenever/if (you do X), then Y happens.”

Pattern:

X と、Y
= When(ever) X happens, Y (naturally) results.

Nuance of と:

It often expresses a natural, automatic, or inevitable result.
Common with things like:
- 春になると暖かくなります。 – When it becomes spring, it gets warm.
- ボタンを押すと、ドアが開きます。 – If you press the button, the door opens.

In your sentence:

深呼吸をすると、ストレスの予防にもなって少し落ち着きます。
= “If/when you take deep breaths, it (naturally) helps prevent stress and you calm down a bit.”

Compared to other conditionals:

〜たら: feels a bit more like “when/if X happens (then on that occasion) Y will happen.” Often used for one-time or specific situations.
〜ば: can feel a bit more hypothetical or logical (“if X, then Y”).
〜と: feels like an automatic result pattern or a general rule.

Here, the author is describing a general rule: “When you do deep breathing, this is what happens.” So と is a very natural choice.

What is the structure and meaning of ストレスの予防? Why is の used?

ストレスの予防 breaks down as:

ストレス – stress
予防 (よぼう) – prevention

の is connecting the two nouns:

A の B can mean many things depending on context:
- possession: 私の本 – my book
- description: 日本の音楽 – Japanese music
- “B for A”: 風邪の予防 – prevention of colds

So ストレスの予防 literally is:

“prevention of stress”
more naturally: “stress prevention” / “preventing stress”

In the sentence, ストレスの予防になる means “it becomes (something that) prevents stress” → “it helps prevent stress.”

What does にも in ストレスの予防にもなって do? What’s the role of に and も together?

にも is simply the combination of two particles: に + も.

に here marks the result or target of なる:
- 〜になる = “to become ~”
- ストレスの予防になる = “to become (to be) stress prevention / to serve as stress prevention”
も adds the sense of “also / too”:
- It suggests “in addition to something else,” or “(even) as X, too.”

So ストレスの予防にもなって implies:

“it also serves as stress prevention”
“it not only helps you calm down, but it also helps prevent stress”

Even though the “other thing” is not explicitly mentioned before, the 構文 naturally suggests:

Deep breathing has at least two benefits in this sentence:
1. It becomes stress prevention (ストレスの予防にもなって)
2. It calms you down a bit (少し落ち着きます)

The も subtly signals “that’s another benefit.”

How does なって work here? What is the function of the て-form of なる?

なって is the て-form of なる (“to become”).

In the sentence:

ストレスの予防にもなって少し落ち着きます。

The structure is:

ストレスの予防にもなる – “(it) becomes stress prevention / serves as stress prevention”
少し落ち着きます – “(you) calm down a bit”

The て-form (なって) connects these two actions/states:

Aて B can mean:
- “A and then B”
- “A and B (as two related things)”

So here, you can understand it as:

“(It) becomes stress prevention, and you calm down a little.”
Or more naturally: “It helps prevent stress and makes you a little calmer.”

The て-form lets the sentence flow as one combined statement of effects instead of using two separate sentences.

Who or what is the subject of 落ち着きます? Why is it not written?

The subject is omitted because Japanese often leaves out what is obvious from context.

In this kind of general advice sentence, the implied subject is typically:

あなた (“you”) in a generic sense, like English “you” meaning “people in general,”
or
“a person who is in that situation.”

So:

少し落ち着きます。 here means
“(You) calm down a little” / “(One) calms down a little.”

Japanese does not need an explicit pronoun as long as it is clear from context.
If you wanted to make the subject explicit, you could (a bit unnaturally) say:

あなたは少し落ち着きます。 – “You calm down a little.”

But in natural Japanese, the pronoun is usually omitted.

Why is 落ち着きます used instead of 落ち着く? Is the tense consistent with 緊張した?

落ち着きます is the polite ます-form of 落ち着く.

落ち着く (dictionary/plain form)
落ち着きます (polite form)

This sentence is written in polite style, so the main verb at the end (落ち着きます) uses the ます-form. That’s why it’s 落ち着きます, not 落ち着く.

About 緊張した:

Subordinate clauses (like 〜とき) can be in plain form even in a polite sentence:
- 忙しいときに来ました。
- 暇なときは本を読みます。
So mixing 緊張したとき (plain form) with 落ち着きます (polite form) is completely normal.

Tense-wise:

緊張したとき: “when (I’ve) become nervous” (past-looking form, but used for the condition/time)
落ち着きます: present polite, describing the general result/effect.

Japanese often uses a past form before とき to mean “once X has happened, …” even in general statements of fact, so this tense combination is standard.

Could I say 落ち着かせます instead of 落ち着きます? What’s the difference between 落ち着く and 落ち着かせる?

They are different verbs:

落ち着く – intransitive; “to calm down (oneself / by oneself).”
落ち着かせる – causative; “to make (someone) calm down,” “to calm (someone/something).”

In the sentence:

少し落ち着きます。 = “(You) calm down a little.”

The idea is that you yourself become calmer as a result of deep breathing, not that you are actively making someone else calm down. So 落ち着く (→ 落ち着きます) is the correct choice.

落ち着かせます would mean you are calming someone else (a child, another person, etc.), which doesn’t fit this context.

Is 緊張したときに a fixed phrase? Could I move it to another position in the sentence?

緊張したときに is not a fixed idiom, but it’s a very common pattern:

[clause] + とき(に) = “when [clause]”

You can move the ときに phrase as a time expression, as long as the meaning stays clear.

Current version:

緊張したときに深呼吸をすると、ストレスの予防にもなって少し落ち着きます。 – When you get nervous, if you take deep breaths, it helps prevent stress and you calm down a little.

Other natural orders include:

深呼吸をすると、緊張したときにストレスの予防にもなって少し落ち着きます。 (Still understandable, but sounds a bit heavier and less smooth.)

The original word order flows nicely: set the condition/time first (緊張したときに), then describe what you do (深呼吸をすると), then the results.

So it’s not a single “set phrase,” but it’s a very standard way to express “when I’m nervous.”

Why are there spaces in the Japanese sentence? Do they have any grammatical meaning?

In normal Japanese writing, words are not separated by spaces:

緊張したときに深呼吸をすると、ストレスの予防にもなって少し落ち着きます。

The spaces in your version are almost certainly added for learners, to help you see each word or phrase:

緊張した｜とき｜に｜深呼吸｜を｜する｜と、｜ストレス｜の｜予防｜に｜も｜なって｜少し｜落ち着きます。

They do not affect grammar or meaning. Japanese native texts (books, newspapers, etc.) almost always write this as a continuous string of characters, with punctuation (。 and 、) but no spaces between ordinary words.