From a clinical perspective adequate instruments to assess the negative impact of stressful dreams and nightmares must be made available. The Nightmare Distress Questionnaire (NDQ) and the Nightmare Effects Survey (NES) are measures that focus on the emotional disturbance and interference caused by nightmares. The objective of this paper is to analyse the psychometric properties of the Spanish version of the NDQ and the NES. The study was carried out on a non-clinical sample composed of 162 university students aged between 18 and 38 years old. The participants completed the following questionnaires: the NDQ, the NES, a Sleep History Questionnaire, the Nightmare Frequency Questionnaire, the Beck’s Anxiety Inventory and the Beck’s Depression Inventory. The NDQ displayed a tri-factorial structure (“preoccupation-fear”, “interference”, and “premonition”), whilst the NES displayed a bifactorial structure (“specific effects” and “general effects”). The NDQ and the NES showed satisfactory levels of internal consistency (with Cronbach’s alphas of 0.80 and 0.87, respectively). Both instruments significantly correlated with anxiety and depression measures. Subjects with a “high frequency of nights with nightmares/disturbing dreams” differed in the NDQ and the NES from those with “low frequency”. In the NDQ the best discrimination value was the direct score of 12 (sensitivity=91.66% and specificity=74.71%), whilst in the NES this involved a direct score of 3 (sensitivity=75% and specificity=67.44%). The results of this study show that the NDQ and the NES are reliable and valid measures that successfully examine the repercussions of nightmares. We discuss the usefulness of the NDQ and the NES in evaluating nightmares within a clinical context.