Learn Hardcore German: Vor dem Schlafen macht sie eine Atemübung im Sitzen, um ihre Haltung zu entspannen. - Before sleeping she does a breathing exercise while sitting in order to relax her posture.

Vor dem Schlafen = a prepositional phrase with a noun
- vor (before) + dem Schlafen (the sleeping)
- Literally: Before the sleeping, idiomatically: Before sleeping
Bevor sie schläft = a full subordinate clause
- bevor (before) + subject sie
  - verb schläft

Meaning: In this context, the meaning is basically the same: she does the exercise before she goes to sleep.

Stylistic differences:

Vor dem Schlafen sounds a bit more compact and noun-based, similar to English before bed / before sleeping.
Bevor sie schläft sounds a bit more like storytelling, with a full clause.

Both are grammatically correct; the sentence just chooses the noun-based version.

Why is Schlafen capitalized and why do we say dem Schlafen?

Here, Schlafen is not used as a verb but as a noun. German can turn infinitives into nouns:

schlafen (to sleep, verb) → das Schlafen (sleeping, the act of sleeping)

Because it's a noun, it is:

Capitalized: Schlafen
Neuter: das Schlafen
In the dative case after vor (for time): vor dem Schlafen

So:

Nominative: das Schlafen
Dative: dem Schlafen
In the sentence: vor dem Schlafen = before (the) sleeping

Could we also say Vor dem Schlafengehen? Is there a difference?

Yes, Vor dem Schlafengehen is very natural and maybe even more common in everyday German.

Schlafengehen = nominalized verb phrase schlafen gehen (to go to sleep)
Vor dem Schlafengehen = before going to sleep / before bedtime

Nuance:

Vor dem Schlafen focuses on the state of sleeping in general.
Vor dem Schlafengehen focuses specifically on the moment of going to bed.

In practice, both can work in this sentence. Many speakers might say:

Vor dem Schlafengehen macht sie eine Atemübung …

Why is the word order Vor dem Schlafen macht sie … and not Vor dem Schlafen sie macht …?

German main clauses follow the verb-second rule (V2):

The finite verb (here: macht) must be the second element in the sentence.
The first element can be the subject, a time phrase, a place phrase, etc.

So:

If the subject is first: Sie macht vor dem Schlafen eine Atemübung …
If a time phrase is first: Vor dem Schlafen macht sie eine Atemübung …

Vor dem Schlafen sie macht … is incorrect, because macht is no longer in second position.

What exactly is eine Atemübung? Why eine and not something else?

Atemübung is a compound noun:

der Atem = breath
die Übung = exercise
→ die Atemübung (feminine) = breathing exercise

Because it’s feminine (die Atemübung) and used as a direct object in the accusative singular, we use:

eine Atemübung (indefinite article, feminine accusative)

Examples:

Nominative: Eine Atemübung hilft ihr.
Accusative: Sie macht eine Atemübung. ✔ (like in the sentence)

What does im Sitzen mean grammatically? Why im and not just Sitzen?

im Sitzen literally means in (the) sitting (position) and functions as an adverbial phrase (describes how she does the exercise).

im = contraction of in dem (in the)
Sitzen = nominalized infinitive of sitzen (to sit), neuter: das Sitzen

So structurally:

in dem Sitzen → im Sitzen

This is a common pattern in German:

im Sitzen = sitting
im Stehen = standing
im Liegen = lying down

You can think of im Sitzen as a fixed expression meaning while in a sitting position / sitting.

What’s the difference between im Sitzen and using a participle like sitzend?

Both can, in theory, express a similar idea, but they are used differently:

im Sitzen is the normal, idiomatic way to say in a sitting position / while sitting.
- Sie macht die Übung im Sitzen.
sitzend is a present participle and is less common as a pure adverb in modern German.
- Something like Sie macht die Übung sitzend is possible but sounds more stylistic or written, and less neutral than im Sitzen.

For everyday language, im Sitzen is the standard and most natural choice.

Could we say beim Sitzen instead of im Sitzen?

Beim Sitzen is grammatically possible but sounds different:

beim = bei dem = during / while
beim Sitzen = while sitting

In this context, im Sitzen is more idiomatic and focuses on the posture/position in which the exercise is done.

Nuance:

im Sitzen: in a sitting posture (how she does the exercise)
beim Sitzen: more like during the act of sitting (less usual in this context)

So for a breathing exercise, im Sitzen is the natural choice.

What is the function of um … zu entspannen? How is it different from für?

um … zu + infinitive introduces a purpose clause:

um ihre Haltung zu entspannen = in order to relax her posture

Structure:

um
- (optional extra words like ihre Haltung) + zu
  - infinitive (entspannen)

We use um … zu when:

It expresses purpose/intention, and
The subject of the infinitive clause is the same as in the main clause.

Here, sie does the exercise and sie relaxes her posture → same subject → um … zu is appropriate.

Why not für?

für
- noun: für ihre Entspannung = for her relaxation (more like for the benefit of, not explicitly purpose as an action)
um … zu entspannen clearly expresses “in order to relax”, i.e. goal/purpose of the action.

So um ihre Haltung zu entspannen is the natural way to say to relax her posture in a purpose sense.

Why is it um ihre Haltung zu entspannen and not um zu ihre Haltung entspannen?

In an um … zu construction, the word order inside the infinitive group is:

Optional objects/complements
zu
Infinitive verb

So:

um ihre Haltung zu entspannen ✔
- object: ihre Haltung
- zu
- verb: entspannen

You cannot put zu at the very beginning of that phrase or in front of the object:

✘ um zu ihre Haltung entspannen
✘ um ihre Haltung entspannen zu

Correct patterns:

um sie zu sehen (to see her)
um das Problem besser zu verstehen (to understand the problem better)
um ihre Haltung zu entspannen

Why is it ihre Haltung and not a reflexive form like sich?

German has both:

sich entspannen = to relax (oneself, generally)
etwas entspannen = to relax something (a specific part, tension, posture, etc.)

In this sentence:

ihre Haltung = her posture is the direct object of entspannen:
- She relaxes her posture (specifically), not just herself in general.

If we said:

… macht sie eine Atemübung, um sich zu entspannen.

that would mean:

… she does a breathing exercise in order to relax (herself) — more general physical/mental relaxation.

So:

um sich zu entspannen = general self-relaxation
um ihre Haltung zu entspannen = specifically relax her posture/body alignment.

What does Haltung mean here? Doesn’t it also mean “attitude”?

Yes, die Haltung has two common meanings:

Posture / body position
- eine aufrechte Haltung = an upright posture
- eine entspannte Haltung = a relaxed posture
Attitude / stance (figurative)
- eine kritische Haltung zu etwas haben = to have a critical attitude towards something

In the sentence:

… um ihre Haltung zu entspannen.

The context is a breathing exercise before sleeping, done sitting, so Haltung clearly means posture here, not mental attitude.

Could we move im Sitzen to another place in the sentence? Would it change the meaning?

Yes, you can move im Sitzen around somewhat; it’s an adverbial phrase. All of these are grammatical and keep the same basic meaning:

Vor dem Schlafen macht sie eine Atemübung im Sitzen, um ihre Haltung zu entspannen.
Vor dem Schlafen macht sie im Sitzen eine Atemübung, um ihre Haltung zu entspannen.
Sie macht vor dem Schlafen im Sitzen eine Atemübung, um ihre Haltung zu entspannen.

Nuance:

Position 1 (end) is very natural: information about how she does the exercise comes after the object.
Position 2 slightly highlights im Sitzen more.
Position 3 flows fine but starts with the subject instead of the time phrase.

The core meaning (she does the exercise in a sitting position) doesn’t change; it’s mostly a matter of emphasis and rhythm.

Why is there a comma before um?

German punctuation rules require a comma before an infinitive clause introduced by:

um, ohne, statt, anstatt, außer, als

In this sentence:

…, um ihre Haltung zu entspannen.

is an infinitive clause of purpose (introduced by um) → comma is mandatory.

So:

Vor dem Schlafen macht sie eine Atemübung im Sitzen, um ihre Haltung zu entspannen. ✔
Without the comma it would be considered incorrect in standard written German.