 Typical symptoms of a hangover may include headache, drowsiness, concentration problems, dry mouth, dizziness, fatigue, gastrointestinal distress (e.g., vomiting, diarrhea), absence of hunger, light sensitivity, depression, sweating, nausea, hyper-excitability, irritability, and anxiety.While the causes of a hangover are still poorly understood, several factors are known to be involved including acetaldehyde accumulation, changes in the immune system and glucose metabolism, dehydration, metabolic acidosis, disturbed prostaglandin synthesis, increased cardiac output, vasodilation, sleep deprivation and malnutrition.Beverage-specific effects of additives or by-products such as congeners in alcoholic beverages also play an important role.