The Hangover

As I managed to dodge one despite a heavy session on Saturday night, I thought it seemed a good use of my time to write about them. They are an inevitability. I have not met one person yet who drinks and has not been crippled by a hangover at some stage to the point where death would be welcomed just to get rid of the horrors of the morning after. Normally, a hangover has standard symptoms: nausea, dizziness, tiredness, headache, aches and pains, photophobia (sensitivity to light), trembling and the fear. But what causes all of the adverse effects and why do they only kick in the next morning? And most importantly can we cure it?

First things first. Alcohol is a toxin. Defined in chemistry as an organic hydrocarbon compound containing a hydroxyl croup. The type that is present in alcoholic drinks is ethanol which is a byproduct of yeasts metabolic process. It is also produced during germination of many plants. Ethanol is a central nervous system depressant. In small doses it acts as psychoactive drug whereby is causes a sense of euphoria, talkativeness and relaxation. However, as you increase the blood alcohol content, you also increase the risks of alcohol poisoning.  I had always thought that when drinking, you lose a fairly large proportion of alcohol through sweating and urine however in actual fact, only 2-8% is disposed of this way, the rest has to be metabolised. When ethanol is degraded by the enzyme alcohol dehydrogenase in the liver**, it is first broken down into acetaldehyde, which is further broken down to acetic acid radicals. Unfortunately, acetaldehyde is a poison that causes immflamation and is closely related to formaldehyde and is thought to be a major contributor to hangovers. Acetaldehyde is degraded fairly quickly by acetaldehyde dehydrogenase and glutathione and if you only have a couple of drinks, it won’t have time to cause any harm. The issue lies in the limited store of glutathione in the liver which cannot handle larger amounts of alcohol, allowing acetaldehyde to accumulate, leaving the toxin in the body for a prolonged period of time.

Process of ethanol metabolism to acetaldehyde (toxin) and finally to acetic acid.

The reason you become dehydrated after consuming alcohol is due to the inhibition of anti-diuretic hormone. This hormone is responsible for maintaining a fluid balance and hydrated state by making you pee out water in your body. You may notice that drinking makes you urinate more and that is a result of depletions of anti-diuretic hormone. You also lose a lot of key electrolytes (salts) in the process. Dehydration itself causes sickness, headache and dizziness on its own. Combine that with the other side effects of alcohol consumption and there is really no wonder why you feel so dreadful first thing the next morning.

Drinking alcohol also induces what is known as the “glutamine rebound”. Hangovers are suggested to be worse due to lack of sleep and it has been found that after a night of alcohol consumption, a drinker won’t sleep soundly. This because alcohol inhibits glutamine, a natural stimulant (thus the sleepiness associated with drinking). Post-drinking, the body over-produces glutamine to make up the difference and as a result causes a restless sleep as well as tremors, anxiety and increased blood pressure

To summarise there are 3 true causes of hangovers:

1. Acetaldehyde toxicity

2. Dehydration

3. Glutamine rebound

The causes of hangovers makes them so difficult to cure. Because consumption of alcohol inhibits certain hormones as well as relying on the finite reserves of natural chemicals, there is no sure fire way of ridding yourself of the sickness, headaches and chronic fear. However Irn Bru, a fry up and a cuddle is a close as any scientist has come so far.

Possibly the worst symptom of a hangover. This picture could not be more accurate.

**Ethanol is not exclusively broken down by alcohol dehydrogenase, other enzymes do contribute but I could spend a whole other (less interesting) post on alcohol metabolism.