Mi esposa es médico, y muchas veces la llaman a las tantas porque hay alguna urgencia.My wife is a doctor and very often they call her in the middle of the night because there's an emergency.
Un ruido me despertó a las tantas de la madrugada, y no pude volverme a dormir.A noise woke me up in the early hours of the morning, and I couldn't go back to sleep.