El dolor de cabeza empeora cuando no descanso bien.

In Spanish, noun phrases often need an article, so el dolor de cabeza is very natural here.

In English, we often say just headache without an article in some contexts, but Spanish usually prefers el with this kind of subject.

Compare:

• El dolor de cabeza empeora... = The headache gets worse...

However, after some verbs, especially tener, Spanish often drops the article:

• Tengo dolor de cabeza. = I have a headache.

So both patterns exist, but in your sentence el dolor de cabeza is the subject of the verb, which makes the article sound normal.

Yes. Dolor de cabeza is the standard Spanish expression for headache.

Literally, it means pain of head or head pain, but you should treat it as a fixed expression meaning headache.

Other similar expressions:

• dolor de espalda = back pain
• dolor de muelas = toothache
• dolor de garganta = sore throat / throat pain

So de cabeza is simply the normal way Spanish specifies what kind of pain it is.

Empeora is the third-person singular form of the verb empeorar = to get worse / to worsen.

The subject is el dolor de cabeza, which is singular, so the verb must also be singular:

• El dolor de cabeza empeora. = The headache gets worse.

A quick mini-conjugation:

• yo empeoro = I get worse / I worsen
• tú empeoras
• él/ella empeora

So it is empeora because the headache is what gets worse, not I.

Yes, you could say Mi dolor de cabeza empeora cuando no descanso bien, and it would be understandable.

But el dolor de cabeza sounds more neutral and natural in many contexts. Spanish often avoids possessives with body parts, symptoms, and physical states when the owner is obvious from context.

So:

• El dolor de cabeza empeora... = natural, general
• Mi dolor de cabeza empeora... = more explicitly my headache

Both are possible, but the version with el is very common.

Because Spanish often drops subject pronouns when they are already clear from the verb ending.

Descanso already means I rest, so yo is not necessary.

• descanso = I rest
• yo descanso = I rest

Adding yo is possible, but usually only for emphasis, contrast, or clarity:

• Yo descanso bien, pero él no. = I rest well, but he doesn’t.

In your sentence, no emphasis is needed, so descanso by itself is the most natural choice.

Because this sentence describes a habitual or general situation: whenever I do not rest well, the headache gets worse.

With cuando, Spanish uses the indicative for things that happen regularly or are considered real:

• El dolor de cabeza empeora cuando no descanso bien.

If you were talking about a future situation, Spanish would often use the subjunctive:

• Cuando no descanse bien, me tomaré algo. = When I don’t rest well, I’ll take something.

So here, descanso is in the present indicative because the sentence expresses a repeated pattern.

Because bien is an adverb, and bueno is an adjective.

Here, the word modifies the verb descanso:

• descansar bien = to rest well

Since it describes how you rest, you need the adverb bien.

Compare:

• Descanso bien. = I rest well.
• Un buen descanso. = A good rest.

So:

• bien modifies verbs
• bueno/buen modifies nouns

Not exactly, though they are close.

• dormir bien = to sleep well
• descansar bien = to rest well

Descansar is broader. You can descansar through good sleep, but also more generally by recovering, relaxing, or getting enough rest.

In this sentence, no descanso bien suggests I’m not getting good rest, which may include poor sleep. In many everyday situations, English speakers might naturally think of it as when I don’t sleep well, but Spanish descansar is slightly wider in meaning.

Yes, absolutely. That version is also correct and natural.

Both mean the same thing:

• El dolor de cabeza empeora cuando no descanso bien.
• Cuando no descanso bien, el dolor de cabeza empeora.

The difference is mainly emphasis:

• starting with El dolor de cabeza puts the focus first on the symptom
• starting with Cuando no descanso bien puts the condition first

Spanish is fairly flexible with this kind of word order.

Empeora is a very good, natural choice.

Another common way to express the same idea is:

• se pone peor = it gets worse

So you could also hear:

• El dolor de cabeza se pone peor cuando no descanso bien.

Both are correct, but empeora is a little more compact and slightly more formal or neutral in tone, while se pone peor can sound a bit more conversational.

It can work either way, depending on context.

• It may refer to a recurring personal symptom: my headache tends to get worse when I do not rest well.
• It may also sound like a general statement about this condition.

Spanish often allows this kind of slightly general wording with el + noun. The exact interpretation comes from context rather than from the grammar alone.