Caffeine, DNA and Cognition

Inclusion Criteria: 1\) adult males and females 18-65 years; 2) who habitually consume caffeine; 3) free from any known disease; 4) free from medication, including contraceptive pills; 5) without uncorrected vision issues, e.g., having myopia but not wearing eyeglasses or daltonism (colour blindness); 6) non-smokers (to avoid contributory effects of nicotine or other tobacco substances to caffeine effects or tolerance) and 7) non-pregnant or breastfeeding. Exclusion Criteria: 1\) individuals with a chronic medical condition, 2) pregnant or lactating women, 3) regularly taking medication, including contraceptive pills, 4) with uncorrected vision, 5) smokers, 6) individuals who habitually consume alcohol more than the publicly recommended upper safe limits (21 and 14 units per week for men and women, respectively) and 7) not providing written informed consent.