­The formal name for a hangov­er is veisalgia, from the Norwegian word for "uneasiness following debauchery" (kveis) and the Greek word for "pain" (algia) -- an appropriate title considering the uncomfortable symptoms experienced by the average drinker. The common hangover includes some or all of the following:

Poor sense of overall well-being

Headache

Sensitivity to light and sound

Diarrhea

Loss of appetite

Trembling

Nausea

Fatigue

Increased heart rate and blood pressure

Dehydration(dry mouth, extreme thirst, dry eyes)

Trouble concentrating

Anxiety

Difficulty sleeping

Weakness

­The most common symptoms are headache, fatigue and dehydration, and the least common is trembling. The severity and number of symptoms varies from person to person; however, it is generally true that the more alcohol a drinker consumes, the worse the hangover will be.



It usually takes five to seven cocktails over the course of four to six hours to cause a hangover for a light-to-moderate drinker (a man who drinks up to three alcoholic beverages a day or a woman who drinks up to one). It may take more alcohol for heavier drinkers because of increased tolerance. Other than the number of drinks consumed, hangovers can be made worse by:

Drinking on an empty stomach

Lack of sleep

Increased physical activity while drinking (dancing, for example)

Dehydration before drinking

Poor health

The reason for some symptoms isn't fully understood, but research has led scientists to have a pretty good understanding of the primary causes of a hangover. In the next sections, we'll find out what's going on in the body to cause these problems.