Learn Hardcore Spanish (Spain): El uso del móvil antes de dormir empeora mi descanso. - The use of the mobile phone before sleeping makes my rest worse.

El uso del móvil antes de dormir empeora mi descanso.
Here the subject is the noun phrase el uso del móvil (the use of the phone).
This sounds slightly more formal and abstract, like talking about the practice / habit of using your phone.
Usar el móvil antes de dormir empeora mi descanso.
Here the subject is the infinitive usar (to use).
This is also correct and a bit more direct and verbal, like using my phone before bed worsens my rest.

Spanish very often turns actions into nouns with an article (el uso, la lectura, el consumo) when they are the subject of the sentence. That’s why el uso del móvil feels very natural here.

What exactly is the subject of the sentence, and what is the object?

Grammatically:

Subject: El uso del móvil antes de dormir
(The whole phrase is what does the action of worsening.)
Verb: empeora (worsens)
Direct object: mi descanso (my rest)

So in English structure:
The use of the phone before sleeping (subject) worsens (verb) my rest (object).

Why is it del móvil and not de el móvil?

In Spanish, de + el (the preposition de plus the masculine singular article el) contracts to del:

de + el móvil → del móvil

You must use the contraction; de el móvil is ungrammatical in standard Spanish.

This only happens with de + el → del and a + el → al.
It does not happen with la, los, las (e.g. de la casa, not dla casa).

Why is it el móvil and not la móvil?

Móvil (meaning mobile phone in Spain) is grammatically masculine, so it takes el:

el móvil = the mobile (phone)

Even though móvil ends in -l, which doesn’t clearly indicate gender, its gender is fixed in the language. You just have to memorize it as a masculine noun.

Is móvil the usual word for “cell phone” in Spain? What about Latin America?

Yes:

In Spain, the normal word is el móvil.
In most of Latin America, people say el celular.

So in Spain you’d say:

Uso mucho el móvil. = I use my phone a lot.

In Latin America:

Uso mucho el celular. = I use my phone a lot.

Your sentence is clearly in Peninsular (Spain) Spanish because of móvil.

Why is it antes de dormir and not antes de que duermo?

Spanish makes a distinction here:

Same subject before and after antes de → antes de + infinitive
- El uso del móvil antes de dormir empeora mi descanso.
  The person who uses the phone and the person who sleeps are the same: yo.
  So: antes de dormir (before sleeping).
Different subject → antes de que + subjunctive
- Apaga el móvil antes de que yo duerma.
  You turn off the phone; I sleep.
  So: antes de que yo duerma, with subjunctive duerma, not duermo.

Antes de que duermo is incorrect; it must be antes de que duerma if you use that structure.

Could I say antes de dormirme instead of antes de dormir? What’s the difference?

Yes, you can say both:

antes de dormir = before sleeping (more neutral)
antes de dormirme = before I fall asleep / before I go to sleep

The reflexive dormirme emphasizes me going to sleep, the moment you drift off.
In everyday speech, Spaniards often say:

Uso el móvil antes de dormirme.
(I use my phone before I fall asleep.)

Both are correct; dormirme just makes it more personal and natural in casual conversation.

Why is it empeora and not something like hace peor?

Spanish has a specific verb empeorar = to make worse / to get worse.

El uso del móvil antes de dormir empeora mi descanso.
= The use of the phone makes my rest worse.

While you could say something like:

El uso del móvil antes de dormir hace que mi descanso sea peor.

…it’s longer and less natural than simply using empeorar.
So Spanish prefers the one-word verb instead of hacer + peor in this kind of sentence.

Why is it empeora and not empeoran?

The verb must agree with the subject, which is el uso (singular):

el uso → third person singular → empeora

If the subject were plural, the verb would be plural:

Los usos del móvil antes de dormir empeoran mi descanso.
(usos = plural, so empeoran)

Why use mi descanso and not just el descanso?

Both are possible, but the meaning changes slightly:

empeora mi descanso
Emphasizes that my own rest is affected. More personal.
empeora el descanso
Sounds more general or impersonal, like rest in general or one’s rest.

In everyday speech, if you’re talking about your own sleep quality, mi descanso is the most natural choice.

What’s the difference between descanso and sueño here?

Both relate to sleep, but they’re not identical:

descanso = rest, overall restoration (can include sleep quality, how rested you feel)
sueño can mean:
- sleep (as a state)
- sleepiness (tiredness, I’m sleepy)
- a dream

In this sentence:

empeora mi descanso
= it makes the quality of my rest worse (how well I recover, how rested I wake up).

If you say:

El uso del móvil antes de dormir empeora mi sueño.

…it’s understandable, but it sounds more like it affects your sleep itself, not just your overall rest. Mi descanso is the more idiomatic choice for “my rest / how rested I feel.”

Can I change the word order, like putting antes de dormir at the beginning or the end?

Yes, Spanish word order is quite flexible. These are all correct:

El uso del móvil antes de dormir empeora mi descanso. (original)
Antes de dormir, el uso del móvil empeora mi descanso.
El uso del móvil empeora mi descanso antes de dormir.

Differences are mostly about emphasis and rhythm:

Starting with Antes de dormir highlights the time frame.
The original order is very neutral and natural: subject → time phrase → verb → object.

Why is it el uso with an article? Could we just say uso del móvil antes de dormir…?

In Spanish, abstract nouns used as subjects almost always take an article:

El uso del móvil antes de dormir empeora mi descanso.
La lectura antes de dormir me relaja.
El consumo de azúcar afecta a la salud.

Saying Uso del móvil antes de dormir empeora mi descanso (no article) sounds wrong to a native speaker. The el is required; Spanish uses articles much more than English in these cases.