Learn Hardcore German: Nach meiner Krankheit brauche ich viel Schlaf, um wieder fit zu werden. - After my illness I need a lot of sleep to become fit again.

Krankheit is feminine: die Krankheit (nominative).
Feminine dative singular of the article is der, and for the possessive mein- it’s meiner.

So:

Nominative: meine Krankheit (my illness)
Dative (after nach): nach meiner Krankheit (after my illness)

Using „nach meine Krankheit“ would be ungrammatical because meine is nominative/accusative, not dative.

Could you explain the structure „um wieder fit zu werden“?

This is an „um … zu + infinitive“ clause, which expresses purpose (in order to …).

um introduces the purpose clause.
wieder fit is the predicate/adjective phrase (again fit).
zu werden is werden in the infinitive with zu (to become).

Literal structure:
viel Schlaf, um (wieder fit) zu (werden) → “a lot of sleep in order to become fit again.”

In German, zu goes directly before the infinitive, and werden goes to the end of the clause.

Why is there a comma before „um wieder fit zu werden“?

Because „um wieder fit zu werden“ is an infinitive clause (Infinitivsatz) describing purpose.

German grammar requires a comma before most „um … zu“ infinitive clauses, especially when they add a separate idea (here: the purpose of needing sleep).

So:
Nach meiner Krankheit brauche ich viel Schlaf, um wieder fit zu werden.
Main clause + comma + infinitive purpose clause.

Why is it „viel Schlaf“ and not „viele Schlaf“?

Because Schlaf here is an uncountable noun (like “sleep” in English).

viel is used with uncountable nouns: viel Wasser, viel Zeit, viel Glück, viel Schlaf.
viele is used with countable, plural nouns: viele Bücher, viele Tage, viele Menschen.

So „viel Schlaf“ = a lot of sleep.
„viele Schlaf“ would be incorrect.

Could I also say „Ich brauche nach meiner Krankheit viel Schlaf“? Is the word order important?

Yes, that sentence is also correct:

Nach meiner Krankheit brauche ich viel Schlaf.
Ich brauche nach meiner Krankheit viel Schlaf.

Both are grammatical. In German, you can move information to the front for emphasis or to follow the time–manner–place tendency.

Starting with „Nach meiner Krankheit …“ puts more emphasis on the time/condition (“after my illness”).
Starting with „Ich brauche …“ starts more neutrally with the subject.

Verb position stays the same: in a main clause, the finite verb (brauche) must be in second position, no matter what comes first.

Why is „brauche“ in the first person singular form?

Because the subject is ich (“I”).

The verb is brauchen (to need).
Present tense:

ich brauche
du brauchst
er/sie/es braucht
wir brauchen
ihr braucht
sie/Sie brauchen

In the sentence:
Ich brauche → “I need” → matches the subject ich.

Why is „fit“ not changed (no ending) even though it describes ich?

„fit“ is used here as a predicative adjective with werden (to become), similar to English:

„Ich werde fit.“ – I become / get fit.

In German, predicative adjectives (used with sein, werden, bleiben etc.) usually have no endings:

Er ist müde.
Sie wird gesund.
Wir bleiben ruhig.
Ich werde fit.

Adjective endings (fitte, fitteN, etc.) appear when the adjective is before a noun:

ein fitteR Mann
eine fitte Frau

But after werden, it stays uninflected: fit.

Could I say „um wieder gesund zu werden“ instead of „um wieder fit zu werden“? What’s the difference?

Yes, you could say:

„… um wieder gesund zu werden.“

Both are correct, but there is a nuance:

fit – often means “fit, in shape, energetic, back to normal functioning.” It can be slightly more informal and can include general performance/energy, not just “not ill.”
gesund – literally “healthy,” mainly about health as the opposite of “ill.”

In many everyday contexts they can overlap, but fit sounds a bit more colloquial and can include being back in good condition, not just technically no longer sick.

Why is it „Nach meiner Krankheit“ and not „Nachdem meiner Krankheit“?

Because „nach“ here is a preposition, not a conjunction.

nach + dative = “after (something)” as a prepositional phrase:
- Nach der Arbeit
- Nach dem Essen
- Nach meiner Krankheit
nachdem is a subordinating conjunction that introduces a full clause with its own subject and verb:
- Nachdem ich krank war, brauche ich viel Schlaf.
  (After I was ill, I need a lot of sleep.)

So you use nach + noun or nachdem + clause. You don’t combine them.

Why is „wieder“ placed before „fit“ and not somewhere else?

Word order inside the „um … zu“ clause has to respect:

The infinitive with zu (zu werden) must go to the end.
Adverbs and adjectives generally come before the verb they modify.

So we get:
um wieder fit zu werden

Other options like:

✗ um fit wieder zu werden
✗ um zu werden wieder fit

are unidiomatic or wrong. The natural order here is: wieder (again) + fit (adjective) + zu werden (infinitive at the end).

Why is „meiner“ used instead of „mir“ in „meiner Krankheit“?

Because „meiner“ here is the possessive determiner (“my”), not the pronoun.

mir = dative form of ich (to me, for me), a pronoun.
meiner (before a noun) = “my” in feminine dative: meiner Krankheit (of my illness / after my illness).

Compare:

Das gefällt mir. – That pleases me. (pronoun)
Nach meiner Krankheit – After my illness. (possessive determiner + noun)

Is „Nach meiner Krankheit“ always about time, or can „nach“ have other meanings?

In this sentence, „nach“ is clearly temporal: after (in time).

But nach can have other uses:

Spatial (direction):
Ich fahre nach Berlin. – I’m going to Berlin.
According to:
Nach meiner Meinung … – In my opinion …
Looking for / after in some fixed expressions:
Er fragt nach dir. – He’s asking about you.

Here, with a noun expressing a condition/time (Krankheit), „Nach meiner Krankheit“ = “after my illness (is over).”

Could I say „Nach der Krankheit brauche ich viel Schlaf“ instead of „Nach meiner Krankheit …“?

Yes, grammatically both are fine:

Nach meiner Krankheit brauche ich viel Schlaf.
Nach der Krankheit brauche ich viel Schlaf.

The difference is nuance:

meiner Krankheit – personalizes it: my illness (the one I had).
der Krankheit – more neutral/generic: “the illness,” maybe referring to a known illness just mentioned in context.

If you want to emphasize that it was your illness, „meiner Krankheit“ is more natural.