Ethanol or ethyl alcohol is the cause of intoxication. As soon as alcohol enters your mouth, some of it enters your bloodstream through tiny blood vessels in your mouth and on your tongue. The severity of an alcohol hangover depends on the amount of alcohol consumed by a person, and whether a person has had enough sleep or not, lack of sleep worsens the condition of an alcohol hangover. It is impossible to estimate how much alcohol consumption causes an alcohol hangover, because it is different for each person and depends on factors such as the person’s tiredness and lack of body water before consuming alcohol, the amount of water they drink at the same time as consuming alcohol, and the amount of sleep a person has after drinking. It depends on drinking alcohol.