Comme Marie manque de sommeil, elle veut se coucher tôt ce soir.

Yes, comme often means like or as, but at the beginning of a sentence it can also mean since or because.

In Comme Marie manque de sommeil, elle veut se coucher tôt ce soir, comme introduces the reason first:

• Comme Marie manque de sommeil = Since/Because Marie is sleep-deprived
• elle veut se coucher tôt ce soir = she wants to go to bed early tonight

This use of comme is especially common when the cause is already known or presented as background information.

Both can mean because, but they are used a little differently.

• Comme usually comes at the beginning of the sentence and sets up the reason as background.
• Parce que more directly answers why? and is often more neutral or emphatic.

So you could also say:

• Marie veut se coucher tôt ce soir parce qu’elle manque de sommeil.

This sounds very natural too. The version with comme simply puts the cause first.

Because the verb manquer normally uses de before what is lacking.

So:

• manquer de sommeil = to lack sleep
• manquer d’argent = to lack money
• manquer de temps = to lack time

In French, de is required here. English often has no preposition in this kind of expression, but French does.

In this expression, sleep is treated as a general, uncountable thing, so French uses de rather than du.

• manquer de sommeil = to lack sleep
• manquer d’énergie = to lack energy
• manquer de patience = to lack patience

Using du sommeil would sound much less natural here. The standard expression is manquer de sommeil.

Not exactly. Even though manquer can sometimes look like to miss, here manquer de sommeil means to lack sleep or to be short on sleep.

That is an important point, because manquer can mean different things depending on the structure:

• manquer de quelque chose = to lack something
  • Elle manque de sommeil.
• manquer quelque chose = to miss something
  • Elle a manqué le train.
• manquer à quelqu’un = to be missed by someone
  • Marie manque à ses amis. = Her friends miss Marie.

So in this sentence, it definitely means she isn’t getting enough sleep.

Because se coucher is the usual verb for to go to bed or to lie down for sleep.

• coucher quelqu’un can mean to put someone to bed
• se coucher means to put oneself to bed / to go to bed

So:

• elle veut se coucher tôt = she wants to go to bed early

The se is reflexive, meaning the action is directed back to the subject.

After a conjugated verb like veut (wants), the next verb stays in the infinitive:

• veut se coucher = wants to go to bed

With reflexive infinitives, the reflexive pronoun stays attached to the infinitive:

• je veux me coucher
• tu veux te coucher
• elle veut se coucher

So se belongs to coucher, not to veut.

Tôt ce soir is the normal order here.

In French, short adverbs like tôt often come before a time expression like ce soir when they modify the action:

• se coucher tôt ce soir = go to bed early tonight

Ce soir tôt sounds unnatural in standard French.

So the sentence order is very natural:

• elle veut se coucher tôt ce soir

French usually needs an explicit subject for each finite verb.

Here there are two clauses:

1. Comme Marie manque de sommeil
2. elle veut se coucher tôt ce soir

In the second clause, French still needs the subject pronoun elle. You cannot normally omit it the way you sometimes can in other languages.

So:

• Marie manque de sommeil, elle veut... = correct
• leaving out elle would not work in standard French

Yes. You can say:

• Comme Marie manque de sommeil, elle veut se coucher tôt ce soir.
• Marie veut se coucher tôt ce soir parce qu’elle manque de sommeil.

Both are natural, but they are not identical in style.

• With comme, the reason comes first and sounds like background information.
• With parce que, the main statement comes first, then the reason.

Using comme after the main clause is much less natural here, so if you want the reason second, parce que is usually the better choice.

Usually, yes. In this sentence, ce soir means tonight.

Literally, it is this evening, but in context it often corresponds to English tonight:

• ce soir = tonight / this evening

Because the sentence is about going to bed, English naturally translates it as tonight.

The original sentence is already perfectly natural, but learners often wonder about alternatives.

Some common variations are:

• Comme Marie manque de sommeil, elle veut se coucher tôt ce soir.
• Marie veut se coucher tôt ce soir parce qu’elle manque de sommeil.
• Marie manque de sommeil, donc elle veut se coucher tôt ce soir.

All are good. The original is slightly more structured because it leads with the cause.