Me lavo la cara antes de dormir.

Because lavarse is often used in Spanish for washing oneself. The me means myself.

So:

• lavo = I wash
• me lavo = I wash myself

In this sentence, Spanish treats washing your face as part of washing yourself, so the reflexive pronoun is natural.

This is very common in Spanish. With reflexive verbs and body parts, Spanish usually uses the definite article instead of a possessive.

So Spanish prefers:

• Me lavo la cara = literally I wash myself the face

rather than:

• Me lavo mi cara

Even though English says my face, Spanish usually says the face when it is already clear whose face it is from me.

Me is the first-person singular reflexive pronoun. It refers back to the subject I.

So in:

• Me lavo la cara

the subject is understood as yo, and me shows that the action comes back to that same person.

It is basically saying: I wash my own face.

In Spanish, object pronouns and reflexive pronouns usually go before a conjugated verb.

So:

• Me lavo la cara

not:

• Lavo me la cara

With an infinitive or gerund, pronouns can attach to the end, but here lavo is a normal conjugated verb, so me goes before it.

Lavo is the first-person singular present tense of lavar.

So:

• yo lavo = I wash

In this sentence, the present tense often expresses a habit or regular action:

• Me lavo la cara antes de dormir = I wash my face before sleeping / before going to bed

It does not have to mean only right now.

After the preposition de, Spanish uses the infinitive when the subject stays general or is the same as the main subject.

So:

• antes de dormir = before sleeping

You cannot say:

• antes de duermo ❌

because duermo is a conjugated form, and after de you need the infinitive: dormir.

Also:

• antes de + infinitive is the normal pattern for before doing something

Because dormir here simply means to sleep.

• antes de dormir = before sleeping

If you said antes de dormirme, that would usually mean before falling asleep, because dormirse often means to fall asleep.

So the version in the sentence is more neutral and natural for before going to sleep / before bed.

It can naturally be understood as before sleeping, and in everyday English that often becomes before bed or before going to sleep.

Spanish often uses antes de dormir in this broad everyday sense, not only in the very literal sense of the exact moment before sleep starts.

Yes. That is completely natural.

Both are fine:

• Me lavo la cara antes de dormir.
• Antes de dormir, me lavo la cara.

The difference is mainly emphasis and word order, not basic meaning.

Yes, but that is normal in Spanish. Spanish often drops subject pronouns because the verb ending already shows the subject.

• lavo already tells you the subject is yo

So:

• Me lavo la cara
• Yo me lavo la cara

Both are grammatical, but the version without yo is more neutral and more common unless you want emphasis.

It is understandable, but it sounds less natural in standard Spanish.

Spanish strongly prefers:

• Me lavo la cara

because:

1. washing your face is usually expressed reflexively, and
2. body parts usually take the definite article in this structure.

So Lavo mi cara is not the usual everyday phrasing.

Yes, very much so. Lavarse la cara is a common everyday expression meaning to wash one’s face.

It follows a broader pattern used with body parts:

• me lavo las manos = I wash my hands
• se cepilla los dientes = he/she brushes his/her teeth
• nos peinamos el pelo = we comb our hair

So this sentence is a very typical Spanish structure.

Yes, absolutely. Me lavo la cara antes de dormir is perfectly natural in Spain.

A speaker in Spain might also say things like:

• Me lavo la cara antes de acostarme = I wash my face before going to bed
• Me lavo la cara por la noche = I wash my face at night

But your original sentence is completely normal and correct.