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.
Dehydration due to ethanol
Ethanol is a diuretic which results in dehydration and an electrolyte imbalance in the body. This causes dizziness, dry mouth and thirst.
Irritation of stomach lining
The nausea that accompanied a hangover is caused when the alcohol irritates the stomach lining.
The first by-product of ethanol Acetaldehyde is roughly 10-30 times more toxic than alcohol. Conversion of acetaldehyde to acetic acid results in a high concentration of acetaldehyde which causes a highly uncomfortable alcohol flush reaction.
Hypoglycaemia is a condition that occurs when blood glucose concentration is decreased due to the dehydrating effect of ethanol.
During the aging and fermentation process, by-products called congeners are added to most alcoholic drinks that already contain ethanol and water. congeners produce residual effects and may potentially also aggravate hangover caused by the ethanol itself.
When drinking, the first metabolite of alcohol named acetaldehyde accumulates in the body causing an alcohol flush reaction. The enzyme alcohol dehydrogenase creates acetaldehyde from ethanol soon after ingestion. The oxidation process then turns it to acetic acid a redox reaction reduces NAD+ (Nicotinamide adenine dinucleotide) to NADH which results in an imbalance. These chemical changes basically make regular bodily functions appear more difficult which is basically what makes a hangover seem like such an otherworldly experience.