Aim: to establish and to analyze a possible relationship between nutritional status, sleep pattern and quality of life in a sample of patients with cognitive dysfunction. Participants and method: an observational, descriptive study of a group of cases with a sample constituted of 48 elderly individuals (aged 65 or over) who agreed to participate in the study and lived in Valencia (Spain). EuroQol (EQ-5D), Oviedo Sleep Questionnaire (OSQ), Mini Mental State de Folsteisn (MMSE) and Mini Nutritional Assessment (MNA) were used in evaluating each individual's case. The association of variables was assessed by correlation between all three variables. Finally, to check the role and predictive capacity of two variables together, a regression model with nutritional status as the dependent variable, sleep pattern as an independent variable and HRQOL as a mediating or suppressing variable was calculated (values of p < 0.05 were considered significant). Results: the average profile of the subjects was that of an 81.5 ± 7.6 year-old widowed woman, with primary education, with 2.40 ± 1.09 children and diagnosed with Alzheimer's disease as principal dementia in 16.7% of the cases. The score of nutritional status (MNA) was 29.95 ± 5.74, for sleep/rest a score of 17.53 ± 11.13 was obtained and for the VAS of the Euro-Qol, 73.70 ± 26.95. Statistically significant Pearson correlations were obtained between the different variables (p < 0.01). Linear regression analysis was applied, with the nutritional status as dependent variable, in relation to the OSQ and the VAS of the Euro-Qol as predictors (independent variables): MNA p < 0.000, OSQ p < 0.014 and VAS p < 0.006. Conclusion: the OSQ score and the VAS score of EQ-5D questionnaire can be considered as independent variables to establish a predictive model for the MNA score (nomogram).