Hangover is a constellation of effects ranging from headache to nausea to what's sometimes called anxiety, which is anxiety that follows a day of drinking. Anxiety, I think we can understand physiologically if we think about that process of alcohol intake increasing the amount of cortisol and the ratio of cortisol to some other stress hormones.

That well explains why some people wake up the day after or even the day after a night drinking and feel anxious and not well and stressed for reasons they don't understand. So if you're somebody who experiences anxiety, then again, I refer you to the master stress episode that we put out some time ago and you can find that hubermanlab.com.

Tools to deal with anxiety, tools to deal with stress ranging again from behavioral to nutritional supplement-based, et cetera. That of course is not justification for going out and drinking so much that you get anxiety-induced hangover. But for those of you that are experiencing post-alcohol consumption anxiety, as it were, that could be a useful resource because I certainly don't want anyone experiencing uncomfortable amounts of anxiety and there are great tools and resources for that.

Now, the other aspects of hangover, such as the stomachache or headache or feelings of malaise or fogginess, those can be related to a number of different things and probably are related to a number of different things. First of all, the sleep that one gets after even just one, yes, even just one glass of wine or a beer is not the same sleep that you get when you don't have alcohol circulating in your system.

And not trying to be a downer here, but this was discussed in the Huberman Lab podcast episode where I had Dr. Matthew Walker from UC Berkeley on, and of course, Dr. Walker is a world expert in sleep, runs one of the preeminent laboratories studying sleep and its effects, wrote the incredible book "Why We Sleep" and so on.

Dr. Walker told me, and it certainly is supported by lots and lots of quality peer-reviewed studies in animals and in humans, that when alcohol is present in the brain and bloodstream, that the architecture of sleep is disrupted. Slow-wave sleep, deep sleep, and rapid eye movement sleep, all of which are essential for getting a restorative night's sleep are all disrupted.

So for those of you that are drinking a glass or two of wine or having a hard liquor drink or a beer in order to fall asleep, the sleep you're getting is simply not high-quality sleep, or certainly not as high quality as the sleep you'd be getting if you did not have alcohol in your system.

Of course, when we're talking about hangover, we're talking generally about the consumption of more than just one or two drinks. Of course, for some people, one or two drinks is probably sufficient to induce hangover, but for most people, it's going to be having three or four, exceeding their typical limit, as it's called.

Again, not the legal limit, that's a whole other business. But when one ingests too much alcohol for them, one of the reasons they feel terrible the next day is because their sleep isn't really good sleep. In fact, it's not even sleep, it's often considered pseudo-sleep, or at least that's what it's called in the sleep science field, because people are in kind of a low-level hypnotic kind of trance, it's not real sleep, they're multiple bouts of waking up, they may not even realize they're waking up multiple times.

Okay, so there's the sleep-induced effects. Then there are the disrupted gut microbiome effects, some of which we talked about earlier, so now you understand the mechanism of alcohol destroying good, healthy gut microbiota, which then leads to leaky gut and things of that sort. But one could imagine, again, could imagine, and there is some evidence starting to support this, that, again, ingesting low-sugar fermented foods or maybe in prebiotic or probiotic to support the gut microbiome might assist in some of the gut-related malaise associated with hangover.

In other words, get those gut microbiota healthy again as quickly as possible, or maybe even before you drink, have those gut microbiota healthy. I would hope that you would do that. I think everybody should be doing something to support their gut microbiome, whether or not it's the ingestion of low-sugar fermented foods daily or at least on a regular basis, or ingestion of probiotic or prebiotic.

The gut microbiome is so important for so many different things. In terms of hangover and headache, we know that that's caused by vasoconstriction, the constriction of blood vessels that tends to occur as a rebound after a night of drinking. Alcohol can act as a vasodilator. It can dilate the blood vessels.

Part of that is associated with the increase in so-called parasympathetic tone. We have an autonomic nervous system. It's got a sympathetic component. These are neurons that make us more alert. And if they're very active, they make us very stressed. There's also the parasympathetic aspect of the autonomic nervous system.

This is all just fancy geek speak for the parts of your brain and body, the nerve cells that make you very relaxed. When you're very relaxed, there tends to be vasodilation. It allows for more movement of blood and other things through the bloodstream. And alcohol tends to induce some vasodilation, at least in some of the capillary beds.

And then when the alcohol wears off, there's a vasoconstriction and people get brutal headaches. That's why some people will take aspirin or Tylenol or Advil or things like that, the sort of non-steroid anti-inflammatories. I should mention, there's a lot of literature coming out that some of these non-steroid anti-inflammatory drugs are not good for us for a number of different reasons.

The way they impact the liver, the way they impact the immune system, and no surprise, the way they impact the gut microbiome. So I'm not one to tell you what medications to take or not take, but you certainly would want to do a quick web search of effects of non-steroid anti-inflammatories and aspirin before you start taking those or stop taking those for that matter.

Generally, they will alleviate headache, but they can often have other issues, including liver issues. And keep in mind the night after drinking, your liver has already taken a beating because of the need of the liver to convert alcohol from acetaldehyde into acetate, which is now a pathway that you well understand.

So I'm not certain. And in fact, I believe it's not the greatest idea to burden your liver further through the use of things that are going to cause it to have to work harder and metabolize things if the goal is simply to alleviate a headache. There's a lot of kind of lore, old school lore about how to relieve a hangover.

We already talked about how eating food won't do that, but eating food will prevent the rapid absorption of even more alcohol into the bloodstream. There's the lore that one should simply ingest more alcohol. What terrible advice that is. That's just going to delay an even worse hangover. However, I'd be remiss if I didn't say that the reason that that myth came to be, or that I should say that truth came to be, because indeed ingesting more alcohol will alleviate a hangover, but then a worse hangover will show up.

The reason that came to be is because ingestion of more alcohol will cause those constricted vessels that are giving the headache to dilate again. But of course, ingesting more alcohol to relieve a hangover is simply a bad idea. Just don't do it. I think this is called the hair of the dog approach.

Maybe someone can put in the show note captions on YouTube why it's called the hair of the dog. I can come up with a few ideas, but they're not going to be very good ones. And some of them would probably even be outright ridiculous. So do not ingest more alcohol simply to try and recover from a hangover.

I know many people have tried that one before, but that's a terrible idea. Now, one thing that you'll also hear out there is that deliberate cold exposure, for instance, taking a cold shower might relieve hangover. I find this one particularly interesting because we've done episodes on the benefits of deliberate cold exposure.

We have an entire episode about that. You can find it again, hubermanlab.com. There are direct links to some of the tools related to deliberate cold exposure. And we have an entire newsletter on deliberate cold exposure protocols you can find on hubermanlab.com, go to our neural network newsletter. So those of you that are interested in ice baths and cold showers and ways to leverage those, you can find that there.

What you won't find there is a description of how to use deliberate cold exposure for sake of treating hangover. But here I went into the literature and I found something kind of interesting. There is some evidence that increasing levels of epinephrine in the bloodstream can actually help with alcohol clearance.

That was very surprising to me. And I want to point out this is not a large and robust literature, but there's some evidence pointing to the fact that when levels of epinephrine adrenaline are raised in the brain and bloodstream, that some of the components of alcohol metabolism can be accelerated and some of the inebriating effects of alcohol can be reduced.

So maybe this old school lore of taking a cold shower actually has something to it. So in thinking about the use of deliberate cold exposure in order to reduce the effects of hangover or to more rapidly clear alcohol from the brain and bloodstream, I want to be very clear and I want to emphasize your safety.

The way to do that is to understand that alcohol lowers core body temperature, okay? It can make people slightly hypothermic. It's going to drop core body temperature. So if you were inebriated and you went and got into a body of water, right? A pool or a lake or something, first of all, that's extremely dangerous to do while you're inebriated, right?

People drown all the time. People drown, they die as a consequence of doing that. So please don't do that. But also if it's a very cold water, your core body temperature is going to drop even further. Now, if you've heard the episodes that I've done on deliberate cold exposure, previously I've talked about how normally when people are not ingesting alcohol, they get into an ice bath or a cold shower and their body temperature initially dips, but then it rebounds and increases.

That's a process that's going to occur when people do not have alcohol in their system. When you have alcohol in your system, one of the reasons that you become hypothermic is because there's a disruption in those hypothalamic brain areas, in particular the brain area called the medial preoptic area that regulates core body temperature.

So it's not so much that alcohol makes you cold, it's that alcohol disrupts the central command centers of the brain that control temperature regulation, and that leads you to be slightly hypothermic. So if you then go get into a very cold lake or you get into even a cold shower or an ice bath, there's the possibility of you going very, very far down the ladder into very hypothermic territory, and that can be very dangerous.

Now, in terms of dealing with hangover, when the alcohol has been largely cleared from your system, well, that's where some of this kind of old lore combines with some of the modern science and says, well, if you can spike adrenaline and certainly getting into an ice bath or getting into a cold shower or any kind of cold body of water, provided you can do that safely, that will sharply increase your adrenaline and I should say your dopamine, that's been shown, and we've talked about this on the podcast before, you get these long extended increases, several hours of increases in dopamine from deliberate cold exposure.

It's well-documented in humans, by the way. So one could imagine using deliberate cold exposure as a way to accelerate the recovery from hangover. Provided that's done safely, I think there's no reason to not explore that, and if you wonder what safely is and what temperatures to use, please check out the episode on deliberate cold exposure.

Cold showers, therefore, might actually be one way to at least partially relieve hangover. Certainly the science from various places in the literature converge to say that, but again, be careful, please, please, please be careful not to get into cold water when you are inebriated. It's absolutely dangerous for all the obvious reasons and it's dangerous also for the non-obvious reasons, not the least of which is the dramatic decreases in core body temperature that can make you dangerously hypothermic.

Now, how would you go about using deliberate cold exposure to accelerate recovery from hangover? Well, there I would look to the kind of standard protocols of, you know, one to three minutes or maybe even six minutes if you can tolerate it, or if you're really cold adapted, maybe you do seven or 10 minutes in a cold shower, although that could be a lot.

Most people are going to experience a sharp increase in epinephrine and adrenaline and a long-lasting increase in dopamine from one to three minutes of deliberate cold exposure, ideally done immersion up to the neck, again, do this safely, please, please, please, or a cold shower where you're getting under the shower as much as possible.

How cold? Well, that's going to vary person to person. I suggest making it as cold as is uncomfortable, such that you really want to get out, but then you know you can stay in safely without, for instance, giving yourself a heart attack, because if the water is really, really cold, of course you can give yourself a heart attack.

Most showers won't go that cold, although probably some will. Again, please use caution, spike your adrenaline, spike your dopamine with deliberate cold exposure safely. Other components of hangover that could be good targets for trying to alleviate hangover, and here I hope you are getting the picture because it is accurate to say that hangover is a multifaceted phenomenon.

It's not like one molecule in one receptor. It's a bunch of things happening in the brain and body, but is the dehydration associated with alcohol. Alcohol is a diuretic for multiple reasons. It causes people to excrete not only water, but also sodium. Sodium is an electrolyte, critical for the function of neurons.

So making sure that you have enough sodium, potassium, and magnesium, so-called electrolytes, is going to be important for proper brain function, bodily organ function. Even for people that have just had one or two drinks the night before, it's likely that your electrolyte balance and your fluid balance is going to be disrupted, and that's because alcohol also disrupts the so-called vasopressin pathway.

I talked a lot about vasopressin and the way that it interacts with and controls different aspects of water retention and water release from the body in the form of urine in the episode on salt. So again, I'm referring to hubermanlab.com as the site where you can find that episode on salt balance and ways to restore electrolyte balance.

Having your electrolytes at the proper levels before you drink is ideal. Some people will say for every glass of alcohol that you drink, you should drink one glass of water. I would say better would be two glasses of water given the dehydrating effects of alcohol, and even better would be water with electrolytes.

That certainly would set you up for a better day the next day. And if you don't manage to do that, 'cause I suppose it's kind of geeky walking around with electrolyte packets out at the bar or whatnot, although, you know, geeky in my book is a good thing, the next day you could take some electrolytes upon waking, maybe even some before you go to sleep at the night of drinking.

So hangovers made worse by disturbed sleep, made worse by disrupted gut microbiome, made worse by disrupted electrolytes, made worse by the depletion of epinephrine and dopamine. That's why replenishing the microbiome with fermented foods, low-sugar fermented foods, that is, that's why using safe, deliberate cold exposure for spiking adrenaline and for increasing dopamine, and that's why consuming electrolytes are all going to be beneficial.

(upbeat music) (upbeat music)