Today I found out what causes a hangover.

There are several things that contribute to hangovers, but one of the principal factors is simple dehydration.  Alcohol has a dehydrating effect by inhibiting the release of vasopressin, which is an anti-diuretic hormone.  So, in layman’s terms,  the result of alcohol inhibiting the vasopressin is that your body produces a lot more urine than normal, with the result that you become dehydrated easily. This dehydration is a major contributor to the headache, dry mouth, and general feeling of lethargy that is often experienced during a hangover.

Another major contributor to a hangover (many think even more significant than dehydration) is acetaldehyde.  Acetaldehyde is produced when alcohol is converted within your body by the enzyme alcohol dehydrogenase to acetaldehyde.  Why’s this bad?  Acetaldehyde is a carcinogen in humans and has been shown to cause damage to DNA, as well as abnormal muscle development when it binds to proteins, among other negative side effects.

Acetaldehyde eventually gets converted to the much more safe (for your body) acetic acid.  However, some people’s bodies contain a genetic deficiency where their bodies don’t convert acetaldehyde to acetic acid very well or at all.  These people have been shown to be significantly more prone to severe hangovers.  They are also ultimately more prone to Alzheimer’s disease, various organ problems, live cancer, and cancer of the upper gastrointestinal tract.

Certain East Asian groups have a mutation in their genetic code that makes their bodies much quicker at converting alcohol to acetaldehyde.  Unfortunately, a large percentage of this group also have a genetic mutation that makes their bodies very slow at converting the acetaldehyde to acetic acid.  Thus, this group is susceptible to hangovers that begin shortly after they begin drinking and last for quite a long time.  For this reason, people who have these particular genetic mutations tend to be very light drinkers, if at all.

A similar type of effect can be produced with the drug Antabuse, which prevents acetaldehyde from converting to acetic acid, so the acetaldehyde stays in your system longer, which typically results in a severe hangover.  For this reason, Antabuse is often used by alcoholics to help quit drinking.

One common myth is that headaches experienced during a hangover are partially caused by alcohol killing brain cells.  In fact, the levels of alcohol one can consume, and live, are insufficient to kill brain cells.  You can read more on this here: Alcohol Does Not Kill Brain Cells

Other Contributing Factors:

• Alcohol consumption also reduces the liver’s ability to effectively remove acetaldehyde and various other toxins from your bloodstream.  This can have various negative effects on your body, depending on the other substances present in your system.
• Alcohol reduces the liver’s ability to compensate for dropping blood glucose levels by inhibiting the liver’s ability to produce glucose.  This results in the brain and your body getting insufficient glucose (the primary energy source for the brain, among other things), which will make you feel fatigued, moody, and weak.  This will also inhibit your ability to concentrate.
• Significant alcohol consumption will also depress your central nervous system.  Once the alcohol has been processed by your body, this results in your nervous system going into a hyperactive state, which can cause you to have a rapid heartbeat and be shaky.
• The alcohol itself will irritate your stomach and intestines.  This may result in abdominal pain, nausea, diarrhea, and vomiting.  The latter two listed will also further dehydrate your body.
• Alcohol also interferes with normal sleep patterns, further contributing to the fatigue you may feel from a hangover.
• Alcohol can also widen blood vessels, further contributing to a headache.

If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (iTunes, Spotify, Google Play Music, Feed), as well as:

• How to Cure a Hangover
• The Good and the Bad of Vaporizing and Inhaling Alcohol
• Alcohol Does Not Help Prevent Hypothermia, It Actually Makes It More Likely
• Alcohol Doesn’t Really “Cook Out” of Food in Most Cases
• That Time the American Government Intentionally Poisoned Certain Alcohol Supplies, Resulting in the Death of Over 10,000 American Citizens

Bonus Facts:

• “Hangover” was a common term in the 19th century meaning “unfinished business”.  Around the early 20th century, the common meaning shifted slightly to mean as it does today.
• As you get older, your body also has less alcohol dehydrogenase available for converting acetaldehyde to acetic acid.  Because of this, most people experience more severe hangovers later in life.