Inclusion Criteria:  Subjects of both sexes (balanced) Caucasian race Ages between 25 and 65 years old (balanced, 50% from 25-45 and 50% from 45-65) Body weight within the normal range (Quetelet index: 19-30) Clinical history, physical examination and vital signs within normality Free acceptance to participate, with written informed consent  Exclusion Criteria:  Previous history of alcoholism or drug dependence (year prior to the screening visit or daily alcohol consumption> 40 gr / day for men or> 24 gr / day for women) Significant consumption of stimulating drinks (> 5 coffees, teas, chocolate or cola drinks / day). Taking any medication in the 15 days prior to the study and / or medicinal plants that may have an effect on the pupil (beta-blockers, droperidol, metoclopramide, clonidine ...). Oral contraceptives and paracetamol will be allowed. Pregnancy (β-hCG test). Menstruation and / or dysmenorrhea on the day of the study Family or personal history or clinical evidence of psychiatric, neurological or ophthalmological problems: anxiety, depression, Parkinson's, glaucoma, dry eyes, retinal diseases, eye surgery and pupil abnormalities, presenting migraine pathology and diabetes Pupillary diameter ≥ 5mm Smokers or ex-smokers <6 months. Have participated in a clinical trial in the 3 months prior to the start of this study.