A hangover occurs when a person has consumed too much alcohol. While many symptoms of a hangover like vomiting erratic motor functions, trembling or shakiness, losing consciousness, hypothermia, stupor and confusion may occur during the drinking session itself. Many other symptoms manifest once the person has woken up after a period of drinking and having fallen asleep. There include photosensitivity, lightheadedness, a sensation of thirst and dehydration, headaches, tiredness and sleepiness etc. While the causes of a hangover are not completely understood even today, experts offer the following reasons that create a hangover.
