dormir

Dormir — "to sleep" — is one of the first verbs every Spanish learner meets, and one of the most useful: you use it every day to talk about how the night went, how the baby is doing, whether you slept on the plane, whether you can sleep over at a friend's. But it is also one of the trickiest verbs at A1, because it carries two vowel changes: the familiar o → ue under stress (duermo, duermes, duerme, duermen), and a second, subtler o → u shift that surfaces in the third-person preterite (durmió, durmieron), the gerund (durmiendo), and the nosotros and vosotros forms of the present subjunctive (durmamos, durmáis).

Only three Spanish verbs follow this exact double-vowel pattern: dormir, morir, and (to a partial extent) poder. Internalize the pattern for dormir and you have done most of the work for morir as well.

The vowel changes — two layers

Spanish -ir stem-changing verbs are sneakier than their -ar and -er cousins. They change in two places:

Layer 1 — o → ue under stress. Whenever the stem syllable carries the spoken stress, o diphthongizes to ue. This happens in four present indicative forms and the matching present subjunctive forms (everywhere except nosotros and vosotros).

Layer 2 — o → u in unstressed weak positions. In -ir verbs only, the stem o weakens to u in three specific environments where the ending starts with an unstressed i or a: the third-person preterite (durmió, durmieron), the gerund (durmiendo), and the nosotros and vosotros present subjunctive (durmamos, durmáis). The -se and -ra imperfect subjunctives also inherit this u (durmiera, durmiese).

Why? Historically, an unstressed o in a syllable next to a stressed i tends to raise to u — it's an old Latin-to-Spanish sound rule that survives in this small group of verbs. You don't need to know the history; you need to recognize that whenever you see dormir with a stem o that isn't stressed, check whether it's the preterite 3rd-person or the gerund — if so, write u.

Non-finite forms

Note that the participle dormido is regular — no u. The change only hits the gerund.

Indicative — simple tenses

Presente — o → ue under stress

The diphthong appears in all forms where the stem syllable is stressed. In dormimos and dormís the stress falls on the ending, so the o stays put.

Pretérito perfecto simple — o → u in 3rd persons

This is the second vowel shift in action. Durmió and durmieron are the forms where most learners slip — the temptation is to write dormió, dormieron by analogy with comió, comieron. Resist it.

Pretérito imperfecto — regular, no changes

The imperfect ending -ía is stressed, so o stays unchanged across all six persons. This is the easiest tense in the paradigm.

Futuro simple

The future is built on the full infinitive dormir-, so no vowel changes occur.

Condicional

Indicative — compound tenses

All compound tenses pair haber with the regular participle dormido — no vowel changes anywhere.

Pretérito perfecto compuesto

Pretérito pluscuamperfecto

Futuro compuesto

Condicional compuesto

Subjunctive — simple tenses

Presente de subjuntivo — o → ue and o → u both appear

This is the most distinctive table in the paradigm: four forms with ue, two forms with u. Nosotros and vosotros are the unstressed positions where -ir stem-changers reach for u instead of staying with o.

Imperfecto de subjuntivo (-ra / -se) — u throughout

The imperfect subjunctive is built from the third-person preterite stem (durmieron → durmie-), which already carries u, so all six persons inherit it. In Spain -ra dominates conversation; -se is more formal or literary.

Subjunctive — compound tenses

Pretérito perfecto de subjuntivo

Pluscuamperfecto de subjuntivo

Imperative

The tú affirmative is duerme (with the diphthong — the stem is stressed). Usted, ustedes, and nosotros affirmatives borrow from the subjunctive: duerma, duerman, durmamos (note durmamos with u). The peninsular vosotros affirmative is dormid — no change, because the ending -id is stressed.

For the reflexive dormirse + vosotros + -os, the final -d drops: dormíos — though in Spain people more often just say dormíos ya or a dormir.

Dormirse: to fall asleep

The reflexive dormirse is not a synonym of dormir. It marks the moment of falling asleep, the transition from awake to asleep — the same logic you find in despertarse (to wake up), acostarse (to go to bed), quedarse dormido (to nod off). Spanish is unusually precise about boundary events; English collapses both onto "sleep" in some contexts.

High-frequency collocations from peninsular Spanish

The classic English-speaker error

English uses one verb, "to sleep," for both the state and many figurative uses. Spanish splits them. The two most common mistakes:

1. Using dormir where Spanish needs dormirse. "I fell asleep on the bus" is Me dormí en el autobús, not ❌ Dormí en el autobús (which means "I slept on the bus" — a long, intentional sleep, not a doze-off).

2. Forgetting the o → u in preterite 3rd-person. "The baby slept all night" is El bebé durmió toda la noche. English-speakers reach for ❌ dormió by analogy with comió, vivió, salió. The u is non-negotiable here.

Common Mistakes

Key Takeaways

• Dormir carries two vowel changes: o → ue under stress (duermo, duermes, duerme, duermen, duerma, duermas, …) and o → u in unstressed positions before i or a (durmió, durmieron, durmiendo, durmamos, durmáis, durmiera, durmiese).
• The participle dormido and the imperfect (dormía) stay regular.
• The vosotros affirmative imperative is dormid; the negative is no durmáis.
• The reflexive dormirse means to fall asleep — the transition, not the state. Don't confuse the two.
• Dormir la siesta is a daily cultural fixture in Spain and the verb of choice for that specific nap.
• The same double pattern appears in morir — learn one and you have most of the other.