Learn Hardcore Swedish: Genom att byta pyjamas blir hon varmare och somnar snabbare. - By changing pajamas she becomes warmer and falls asleep faster.

Genom att + infinitive means “by (doing something)” / “through (doing something)” and expresses the means or method by which something happens.

So Genom att byta pyjamas literally is “By changing pyjamas”, telling us how she becomes warmer and falls asleep faster.

Grammar-wise:

genom = a preposition, “through / by”.
att = the infinitive marker (“to” in English).
byta = the infinitive form of the verb (“change”).

This whole phrase functions as an adverbial at the beginning of the sentence, modifying the verb blir (“becomes/gets”).

Why is it byta pyjamas and not byter pyjamas?

byta is the infinitive form (“to change”), and it appears because of att.

Structure:

att + infinitive → att byta (“to change”)
So after genom att, you must use the infinitive form, not a finite verb.

byter is the present tense form (“changes / is changing”), used when there is a normal subject and verb, for example:

Hon byter pyjamas. – “She changes (her) pyjamas.”

In the original sentence we don’t have a full finite clause there; we have an infinitive phrase introduced by genom att, so byta is correct.

Why is there no article in byta pyjamas? Why not byta en pyjamas?

Swedish often drops the article in some very common verb + noun combinations, especially with:

clothing
means of transport
musical instruments
some activities

For example:

köra bil – to drive a car
spela piano – to play the piano
byta tröja – to change (one’s) sweater

Similarly, byta pyjamas is a natural, idiomatic expression meaning “change (one’s) pyjamas”.

You can say byta en pyjamas, but that sounds more like changing one specific pyjamas (out of several), and is less idiomatic in this context. The version without the article feels more general and natural.

Where is “her” in the Swedish sentence? Why doesn’t it say hennes pyjamas or sin pyjamas?

Swedish often omits possessive pronouns (like “her”, “his”) when it is obvious that something belongs to the subject, particularly:

body parts
clothes the person is wearing

For example:

Hon borstade håret. – “She brushed her hair.”
Han tog av jackan. – “He took off his jacket.”

In the sentence Genom att byta pyjamas blir hon varmare..., it’s automatically understood that it’s her pyjamas. Saying hennes pyjamas would be possible, but it often sounds unnecessary or even slightly marked if it’s clearly about her own clothes.

Is pyjamas singular or plural in Swedish?

In Swedish, pyjamas is normally treated as a singular word:

en pyjamas – “a pair of pyjamas”
pyjamasen – “the pyjamas”

The plural is:

pyjamasar / pyjamaser – “pyjamas (several pairs)”

In everyday speech you’ll usually meet it in the singular when talking about what one person is wearing, as in this sentence. The form pyjamas (without article) here functions as a singular object of the verb “change”.

Why is it blir hon varmare and not hon blir varmare?

This is due to the Swedish V2 word order rule: in a main clause, the finite verb must be in second position, no matter what comes first.

The sentence starts with the adverbial phrase Genom att byta pyjamas (1st element).
Therefore, the verb blir must come next (2nd element).
The subject hon then comes after the verb.

So the word order becomes:

Genom att byta pyjamas (1) blir (2) hon (3) varmare...

If you removed the initial phrase, the “neutral” order would be:

Hon blir varmare och somnar snabbare. – “She gets warmer and falls asleep faster.”

Why is blir used instead of är? What is the difference between blir varmare and är varmare?

blir focuses on a change of state (“becomes / gets”), while är describes a state (“is”).

Hon blir varmare. – She gets/becomes warmer (there is a change).
Hon är varmare. – She is warmer (already in that state).

In the sentence, changing pyjamas causes a change: she goes from being less warm to more warm. That’s why blir varmare is used.

What is the difference between somnar and sover?

They describe two different things:

somnar – “falls asleep”, the process of going to sleep (inchoative).
- Hon somnar snabbt. – “She falls asleep quickly.”
sover – “sleeps”, the state of being asleep.
- Hon sover djupt. – “She sleeps deeply.”

In the sentence somnar snabbare, the focus is on how quickly she falls asleep, not on how she sleeps after that, so somnar is the correct verb.

Why is it snabbare and not something like mer snabb?

snabbare is the regular comparative form of the adjective/adverb snabb (“fast”).

Comparative pattern for most short adjectives:

snabb – fast
snabbare – faster
snabbast – fastest

The same form is used adverbially (like English fast/faster):

Hon springer snabbare. – She runs faster.
Hon somnar snabbare. – She falls asleep faster.

Using mer snabb would sound unnatural here; snabbare is the idiomatic way.

Could you say Genom att byta om till pyjamas instead of Genom att byta pyjamas? Is there a difference?

Yes, you can say Genom att byta om till pyjamas; it’s very natural Swedish.

byta om = “to get changed / change clothes (in general)”
byta om till pyjamas = “change into pyjamas”
byta pyjamas = “change (one’s) pyjamas”

Subtle difference:

byta pyjamas suggests changing from one pyjamas to another.
byta om till pyjamas highlights the target outfit (putting on pyjamas, maybe from day clothes).

Context usually makes it clear, and both versions work well in many situations.

Why is there no comma after pyjamas: Genom att byta pyjamas blir hon...?

Modern Swedish uses fewer commas than English, especially between a fronted adverbial and the main clause.

You normally do not put a comma between:

an introductory adverbial phrase (like Genom att byta pyjamas)
and
the main clause (blir hon varmare och somnar snabbare)

So:

Genom att byta pyjamas blir hon varmare... ✔
A comma there is not wrong in a very long or complex sentence, but the default, natural style is to leave it out.