I was just wondering how exactly alcohol affects the brain, but mainly about the hangover symptoms… when they begin, how long they last…
I was wondering about this, because I feel like my hangover headache begins way earlier than it’s supposed to…
In: Biology
The drunk/hungover thing is modulated by relative levels of two chemicals in the blood: Alcohol (ethanol) and something called acetaldehyde. TL;DR: Ethanol is the drunk chemical, acetaldehyde is the hungover chemical. Acetaldehyde is the first step the body takes to get rid of ethanol, and after large amounts of alcohol, you get a big buildup of acetaldehyde that takes a while to clear out.
Ethanol, the alcoholic bit of an alcoholic beverage, does a lot of different things, but the main thing it does is suppresses signals in the brain. The way signalling in the brain works is that each cell is essentially always doing some maths to figure out whether it should send a signal or not. The maths it does is simple addition: Each of the cells that its linked to shouts a number at it, and it adds all those numbers up. If the total is 70 or higher, it decides it should send a signal, and that signal it sends is a signal that will shout a number at a bunch of other cells. In this way, you get a chain of number-shouting and maths. What ethanol does here is it shouts negative numbers (or rather, it tricks the cell into thinking that it’s having negative numbers shouted at it). So when a cell would normally hear say, 30 + 30 + 20 + 10 – 15 (a total of 75, on which it would fire), the ethanol makes that -15 sound like -30, so the cell thinks it’s hearing a total of 60, and doesn’t fire. Of course, in actual biology this is way more complicated and involves electrical charges, but the underlying logic is the same, and ethanol makes cells less likely to send their signals. Ethanol is basically telling the brain to not do what it wants to do.
Acetaldehyde meanwhile doesn’t do this, but it is much more toxic. It does more active, long term damage, even killing cells, and the body has evolved to feel pain when conditions get too poisonous, as if to say “stop eating poison for fucks sake”.
Ethanol is poisonous, so the body wants to get rid of it. Except for some reason, the first step on this is to turn all the ethanol into acetaldehyde – a *more* toxic chemical. After that, the acetaldehyde is converted into something called acetic acid, which is harmless. Normally, both these conversion processes happen simultaneously, so when you only drink a small amount of alcohol, it gets converted into acetaldehyde but then immediately converted into acetic acid, meaning no hangover. However, this process can get backed up, because both conversions require the same secondary component (a molecule called NAD). NAD isn’t consumed, but it gets contaminated, and the cells take time to clean it up. Drink too much alcohol, and NAD is being contaminated faster than it can be cleaned, which causes an accumulation of acetaldehyde. Also, fun fact, one of the processes that cleans NAD is the creation of fat molecules, which is why alcohol has a strong link to gaining weight: the abundance of contaminated NAD makes the body produce a bunch of fat molecules so as to clean the NAD.
So what you get is drunkness, and then hungoverness. First you drink a bunch of alcohol, and wuh-hey, now you’re drunk cos there’s loads of ethanol telling your brain not to do stuff! Meanwhile, the liver is furiously trying to convert that ethanol into harmless acetic acid, but there’s so much ethanol it gets jammed up. A few hours later, the body has converted most of the ethanol, but it’s got stuck as acetaldehyde, which is much more poisonous and doesn’t do any of the fun brain stuff, so instead of a nice drunk buzz you’ve just got pain. It will still be another few hours before the liver finally unjams and can convert that huge amount of acetaldehyde into harmless acetic acid.
There’s also a bunch of other things going on simultaneously, like being really dehydrated, but it seems that this ethanol – acetaldehyde – acetic acid balance is the main component.
If your hangovers start too early, it may be because the molecules that convert ethanol into acetaldehyde are more common in you than normal, so acetaldehyde builds up faster, or it may be because the molecules that convert acetaldehyde into acetic acid are less common in you than normal (or not as efficient), so acetaldehyde is drained slower, or it may be another thing that isn’t either of those things.
ELI5: You are drunk from ethanol (alcohol) in your body which interferes with the normal operations within your body. Then your liver breaks down the ethanol into a lot of compounds, of which acetaldehyde is the main contributor to hangover symptoms. From there, acetaldehyde is broken down and excreted/released as acetic acid.
Most hangover symptoms are due to the lack of judgement, low impairment, numbing and pain killing effects of alcohol. If you drink a lot you will usually do things your body is not capable off without getting damaged and you do not notice because you are drunk. However as your body breaks down the alcohol and you sober up the symptoms are no longer masked.
There are also toxins generated as a byproduct of the body breaking down alcohol. And although they do not cause the severy symptoms normally associated with a bad hangover there is some milder symptoms that could be explained by some of these. Most notably acetaldehyde which is a byproduct of alcohol breakdown which is known to cause headaches in clinical trials. There is still active research on this but for now it does not seam like this is the main cause of headaches in hangover. All the dehydration, sensory overload, lack of sleep, etc. that comes with a night out is probably the main cause of headache. And there is a very effective antidote to acetaldehyde in caffeine which is not as effective in real hangover patients as in clinical trials with acetaldehyde.
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