How to Say "bad dreams" in Spanish
The Spanish word for “bad dreams” is “pesadillas” — A2 level. This is a very common word in everyday Spanish.

Examples
Tuve pesadillas horribles después de ver esa película de terror.
I had horrible nightmares after watching that horror movie.
Las pesadillas de la guerra lo persiguen todavía.
The nightmares of the war still haunt him.
Arreglar el coche se convirtió en una pesadilla de gastos y demoras.
Fixing the car turned into a nightmare of expenses and delays.
Always Plural
Even when you are talking about just one scary dream experience, Spanish usually uses the plural form 'pesadillas' (nightmares) when talking about the general occurrence of bad dreams.
Using 'sueños malos'
Mistake: “Usar 'sueños malos' para decir 'nightmares'.”
Correction: Although 'sueños malos' literally means 'bad dreams,' the standard and much more common word for 'nightmare' is 'pesadilla' (singular) or 'pesadillas' (plural).
Related Translations
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