Learn Hardcore Russian: Когда мне не спится ночью, я выхожу на балкон и дышу глубоко. - When I can’t sleep at night, I go out onto the balcony and breathe deeply.

Мне не спится is an impersonal construction meaning “I can’t sleep / I’m unable to fall asleep,” often implying it’s not fully under your control (restless, insomnia, thoughts, etc.).
Я не сплю simply means “I’m not sleeping” (I’m awake), which can be deliberate or neutral.

What case is мне, and why is that case used?

Мне is dative. In impersonal “state” constructions (like мне холодно, мне не работается, мне не спится), Russian often uses the dative for the person experiencing the state—roughly “to me / for me.”

What does -ся do in спится?

Here -ся forms an impersonal verb meaning “to sleep (successfully/easily),” often about how sleep “comes” to someone.
So (не) спится ≈ “(not) able to sleep / (not) sleepy / sleep doesn’t come.”

Why is it спится (present tense) if the sentence talks about “when” something happens?

Russian often uses the present tense after когда to express a repeated or typical situation:
Когда мне не спится ночью, ... = “When(ever) I can’t sleep at night, ...” (a habitual pattern).

What’s the difference between ночью and по ночам here?

Ночью = “at night” (can be general or about a particular night, depending on context).
По ночам more strongly suggests repetition: “at nights / at night-time (regularly).”
Both can work; по ночам would sound more explicitly habitual.

Why is there a comma after ночью?

Because the sentence starts with a subordinate clause:
Когда мне не спится ночью, (subordinate “when” clause) я выхожу... (main clause).
In Russian, this comma is required.

Why is it выхожу на балкон and not выхожу на балконе?

На балкон uses accusative and means motion to the balcony (destination).
На балконе uses prepositional and means location on the balcony (where you are).
So: я выхожу на балкон (I go out onto the balcony), then you could add и на балконе дышу... if you wanted to emphasize location.

What aspect is выхожу, and what nuance does it add?

Выхожу is imperfective. In this context it suggests a habitual/repeated action: “I (usually) go out.”
If you meant one specific time, you might use perfective: я выйду на балкон (“I’ll go out onto the balcony”) or я вышел (“I went out”).

Can the word order be changed? For example: Я выхожу на балкон, когда мне не спится ночью.

Yes. Both are natural.
Starting with Когда... foregrounds the condition (“When I can’t sleep…”).
Putting it at the end can make the main action feel primary (“I go out… when I can’t sleep…”). The comma still separates the clauses.

Why is глубоко placed after дышу? Can it be глубоко дышу?

Both are possible.
дышу глубоко is neutral and common.
глубоко дышу puts more emphasis on глубоко (“deeply”). Russian word order is flexible and often used for emphasis.

Is дышу imperfective, and does that matter?

Yes, дышать → дышу is imperfective. Here it matches the idea of an ongoing activity you do for a while (“I breathe deeply”). A perfective form isn’t normally used for this simple “breathe” meaning.

Is there anything tricky about spelling/pronunciation in спится?

Common pitfalls:

It’s спится (no extra ь): not спиться.
Pronunciation: спИтся with stress on и.