Short-term effects of alcohol consumption include intoxication and dehydration. Long-term effects of alcohol consumption include changes in the metabolism of the liver and brain and alcoholism (alcohol dependency). Alcohol intoxication affects the brain, causing slurred speech, clumsiness, and delayed reflexes. Alcohol stimulates insulin production, which speeds up glucose metabolism and can result in low blood sugar, causing irritability and (for diabetics) possible death.  Severe alcohol poisoning can be fatal. However, not all effects of alcohol consumption are harmful. Although even moderate alcohol consumption increased the risk of death in younger people, it has been shown to decrease the risk of death for individuals ages 55+ (due to decreased risk of ischemic heart disease). The median lethal dose of alcohol in test animals is a blood alcohol content of 0.45%. This is about six times the level of ordinary intoxication (0.08%), but vomiting or unconsciousness may occur much sooner in people who have a low tolerance for alcohol. The high tolerance of chronic heavy drinkers may allow some of them to remain conscious at levels above 0.40%, although serious health dangers are incurred at this level. Alcohol also limits the production of vasopressin (ADH) from the hypothalamus and the secretion of this hormone from the posterior pituitary gland. This is what causes severe dehydration when alcohol is consumed in large amounts. It also causes a high concentration of water in the urine and vomit and the intense thirst that goes along with a hangover. Stress, hangovers and the oral contraceptive pill may increase the desire for alcohol because these things will lower the level of testosterone and alcohol will acutely elevate it. Tobacco has the same effect of increasing the craving for alcohol.