J’ai beau dormir huit heures, j’ai encore mal à l’épaule et au front quand je me réveille.

Avoir beau + infinitive is an idiomatic French structure. It means something like:

• even though I ...
• no matter how much I ...
• I may well ..., but ...
• despite ...-ing

So:

• J’ai beau dormir huit heures, ...
  = Even though I sleep for eight hours, ... = No matter how much I sleep eight hours, ... = I may sleep eight hours, but ...

The basic idea is: the action happens, but it does not produce the expected result.

In this sentence, the expected result would be: if I sleep eight hours, I should feel better. But that does not happen.

No. In j’ai beau dormir, beau does not mean beautiful.

Normally, beau is an adjective meaning beautiful / handsome / nice. But in the expression avoir beau + infinitive, it is part of a fixed idiom and has a completely different meaning.

So you should learn avoir beau as a whole expression, not by translating beau word for word.

Because avoir beau is followed by an infinitive.

Pattern:

• j’ai beau essayer
• tu as beau expliquer
• il a beau travailler
• nous avons beau attendre

So here:

• J’ai beau dormir huit heures...

That is the normal grammar of the construction.

In French, a duration can often be used directly after the verb without pendant.

So:

• dormir huit heures = to sleep for eight hours

This is very natural French.

You could also say:

• dormir pendant huit heures

but in many everyday sentences, pendant is unnecessary.

So huit heures here is simply expressing duration.

Here, encore means still.

• j’ai encore mal = I still have pain / I still hurt

That makes sense because the sentence contrasts expectation and reality:

• I sleep eight hours,
• but I still have pain.

In other contexts, encore can mean again, but here still is the natural meaning.

French commonly uses the expression avoir mal to talk about pain.

• j’ai mal = I’m in pain / it hurts
• j’ai mal à l’épaule = my shoulder hurts / I have pain in my shoulder

This is different from English, where we often use hurt as a verb:

• My shoulder hurts

In French, the very common pattern is:

• avoir mal à + body part

So this sentence uses a very standard French way of expressing pain.

Because after avoir mal à, French normally uses the definite article with the body part:

• avoir mal à la tête
• avoir mal au dos
• avoir mal à la jambe
• avoir mal à l’épaule

So:

• à l’épaule = in the shoulder
• au front = in the forehead

This is one of those places where French and English work differently. English often prefers a possessive:

• my shoulder
• my forehead

French often prefers:

• the shoulder
• the forehead

especially with body parts.

Because of article contraction.

• à + le = au
• à + la = à la
• à + l’ = à l’
• à + les = aux

So:

• le front becomes au front
• l’épaule stays à l’épaule

Why l’épaule? Because épaule starts with a vowel sound, so the article is l’ instead of la.

Because the speaker is referring to pain in one shoulder and the forehead.

So:

• à l’épaule = in the shoulder
• au front = in the forehead

If both shoulders hurt, French could say:

• j’ai mal aux épaules

using aux because it is à + les.

So the singular here is just because the sentence is talking about specific singular body parts.

Because these are two separate clauses:

1. J’ai beau dormir huit heures
2. j’ai encore mal à l’épaule et au front

The first clause sets up the contrast: even though I sleep eight hours.
The second clause gives the result that is surprising or disappointing: I still have pain.

French often repeats the subject and verb clearly in each clause, just as English does:

• Even though I sleep eight hours, I still have pain...

So the repetition is normal and necessary.

This uses the reflexive verb se réveiller, which means to wake up.

Its conjugation includes a reflexive pronoun:

• je me réveille = I wake up
• tu te réveilles = you wake up
• il se réveille = he wakes up

So:

• quand je me réveille = when I wake up

French often uses a reflexive verb where English does not.

Compare:

• French: je me réveille
• English: I wake up

The me does not mean myself in a strong way here; it is just part of the normal verb structure.

Because réveiller and se réveiller are different.

• réveiller quelqu’un = to wake someone up
• se réveiller = to wake up

So:

• je réveille Paul = I wake Paul up
• je me réveille = I wake up

If you said quand je réveille, it would sound incomplete unless you added an object, because réveiller by itself usually means waking someone else.

Because it tells us when the pain happens.

The main idea is:

• I still have pain in my shoulder and forehead

Then French adds the time clause:

• quand je me réveille = when I wake up

This placement is very natural. French can often put a time expression either at the beginning or the end, depending on style and emphasis.

For example, both are possible:

• Quand je me réveille, j’ai encore mal...
• J’ai encore mal... quand je me réveille.

In your sentence, putting it at the end sounds smooth and natural.

Not really. A word-for-word translation would sound awkward because several parts are idiomatic.

For example:

• J’ai beau... is not translated literally.
• j’ai mal à... is not translated literally.
• je me réveille uses a reflexive form that English does not.

A more natural English rendering would be something like:

• Even though I sleep eight hours, I still have pain in my shoulder and forehead when I wake up.
• I may sleep for eight hours, but I still wake up with pain in my shoulder and forehead.

So this is a good example of a sentence that should be understood by structure and meaning, not by direct word-for-word matching.