Du burde gå i seng tidligt, hvis du er meget træt.

Burde is a modal verb meaning should or ought to.

In this sentence, it gives advice or says what would be a sensible thing to do. It is not as strong as a command.

So Du burde gå i seng tidligt means that going to bed early is probably the right idea.

Yes. Du bør gå i seng tidligt is also correct.

A useful rough difference is:

• burde often sounds a bit softer or more conversational
• bør can sound a bit firmer, more formal, or more like general advice

In many everyday situations, both are possible. As a learner, it is good to recognize both.

Gå i seng is a fixed Danish expression meaning go to bed.

You should learn it as a whole phrase rather than translate each word separately.

A very important detail is that Danish normally says:

• gå i seng = go to bed
• være i seng = be in bed

You do not usually add the definite article here.

So:

• Jeg går i seng nu = I am going to bed now

But i sengen would usually mean in the bed, referring more literally to the bed itself.

Because tidligt is functioning as an adverb here.

The adjective is tidlig = early, but when Danish uses this kind of word to describe an action, it often takes the -t form:

• en tidlig morgen = an early morning
• at stå tidligt op = to get up early
• at gå i seng tidligt = to go to bed early

So here tidligt describes how or when you should go to bed.

Hvis means if and introduces a condition.

So hvis du er meget træt means if you are very tired.

This is different from når, which usually means when in the sense of something expected or repeated.

Compare:

• Hvis du er meget træt = if you are very tired
• Når du er træt, går du tidligt i seng = when you are tired, you go to bed early

So in your sentence, hvis is used because the second part gives a condition for the advice.

Because hvis du er meget træt is a subordinate clause.

In Danish, the special verb-second rule mainly applies to main clauses. In a subordinate clause introduced by words like hvis, at, fordi, and som, the order is normally:

• conjunction
• subject
• verb

So:

• hvis du er meget træt

not:

• hvis er du meget træt

That is normal Danish subordinate-clause word order.

Because meget is used to mean very or much, while mange means many.

Here meget modifies the adjective træt, so it means very tired.

Compare:

• meget træt = very tired
• mange bøger = many books

So mange cannot be used before træt here.

Yes, absolutely.

You can say:

Hvis du er meget træt, burde du gå i seng tidligt.

This has the same basic meaning, but the condition comes first.

Notice what happens in the main clause after the fronted hvis clause:

• burde du
• not du burde

That is because the main clause still follows the Danish verb-second pattern.

The comma is common and correct, but whether it is required depends on the comma system being used.

In modern Danish, some writers use start comma, and some do not. So you may see both:

• Du burde gå i seng tidligt, hvis du er meget træt.
• Du burde gå i seng tidligt hvis du er meget træt.

Both can be correct depending on style and punctuation choice.

As a learner, the main thing is to recognize that hvis du er meget træt is a subordinate clause.

Yes. Du is the normal singular you in modern Danish and is used in almost all everyday situations.

There is also a formal De, but it is much less common and can sound very formal, old-fashioned, or specially polite depending on the context.

So for ordinary conversation, du is exactly what you would expect here.