Most of us know that drinking too much can lead to car accidents, addictions or worse. We know drinking a little can make us giggly or weepy, lose our balance or lose our lunch, feel ravenously hungry the morning after or want nothing more than to be still in a dark room until that terrible pounding subsides.
But few of us know much more than the above, especially when it comes to what’s actually going on inside the body to create these reactions.
In fact, alcohol, even in the smallest doses, affects nearly every system in the body, from the brain to circulation to immunity. And while at low to moderate doses, alcohol does seem to provide certain health benefits — including a longer life and a healthier heart — at higher doses, drinking carries with it the risk for long-term effects and permanent damage.
The holiday season in general — and New Year’s Eve in particular — is rife with opportunities to drink alcohol — and to overdo it.
In fact, those champagne toasts can come with some serious consequences. Two to three times more people die in alcohol-related car accidents during the week of Christmas and New Year’s than other comparable time periods. During the rest of December, 28 percent of traffic-related deaths involve a drunk driver; that number jumps to 40 percent during the week of Christmas and New Year’s. Visits to the emergency room for alcohol-related illness or injuries also increase on New Year’s Day, by as much as two or 2.5 times.
Of course, you can responsibly toast to 2013. A standard drink is considered .6 ounces of pure alcohol, the equivalent of about 12 ounces of beer, eight ounces of malt liquor, five ounces of wine or 1.5 ounces of hard liquor, according to the CDC.
Experts typically define moderate drinking as one drink a day for women and up to two for men. Binge drinking is only a few rounds away; it’s categorized as four or more drinks on a single occasion for women and five or more for men.
When it comes to being legally drunk, however, we measure alcohol consumption not by drinks, but by blood alcohol level or blood alcohol content (BAC), a measurement of the alcohol present in the blood. (Alcohol in the breath and urine mirrors the BAC.) The National Highway Traffic Safety Administration sets the legal definition of “drunk,” as it pertains to driving impairment, at .08.
BAC is affected by gender, weight, how much and how recently you’ve eaten and how long you’ve been drinking, so it can be tricky to say how many drinks it takes to reach a given BAC. There are, however, some estimates and even online calculators that can approximate BAC, roughly.
While it’s not an exact science, Aaron White, Ph.D. a health scientist administrator at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), says intoxication is typically divided into three ranges. A low dose of alcohol would cause a BAC of up to .05. Anywhere from .06 to .15 would classify as a moderate dose of alcohol, and a high dose would be anything above that.
Because the volume of water in the body directly affects BAC, experts recommend alternating between alcoholic drinks and non-alcoholic ones this New Year’s Eve (and whenever multiple drinks might be on the menu). “It helps with the effects of dehydration, and, if you’re holding a bottled water, it still gives you something to do with your hands,” says Gary J. Murray, Ph.D., the acting director of the Division of Metabolism and Health Effects at the NIAAA.
We spoke to Murray, White and Dr. Michael Fingerhood, an associate professor of medicine at Johns Hopkins Bayview Medical Center’s Comprehensive Care Practice, to find out just what happens in the body when we drink alcohol. Keep these in mind as you ring in 2013.
Mouth
Alcohol isn’t in the mouth for very long, so the enzymes that begin to break it down don’t have much time to do their work. While a little is digested, most of your drink passes on to the stomach.
Stomach
Alcohol will pass more slowly through the stomach if you’ve eaten recently, allowing for more of it to be broken down before it reaches the liver, so eating before or while drinking really does slow down your buzz. And that’s a good thing! Alcohol irritates the lining of the stomach, which can bring on nausea or vomiting.
Famished? That drink is also tricking your stomach to think it’s receiving fuel, as alcohol is high in calories but doesn’t provide any real food, which might explain why some people feel compelled to eat while intoxicated, or are especially hungry the next day.
Liver
The liver is responsible for breaking down most of the alcohol (now in the form of acetaldehyde) in the second stage of metabolism. Here, the second class of enzymes converts the toxic acetaldehyde into harmless acetate, which is close in chemical makeup to vinegar.
The liver can only metabolize a certain amount of alcohol per hour, no matter how much you’ve actually had. So why does it seem like some people can drink more than others? This rate varies between individuals, and is also affected by gender and how much you’ve had to eat that day. Plus, certain groups of people seem to have particularly low-functioning enzymes or lack the enzymes altogether, inhibiting the completion of this second phase of alcohol metabolism (this is commonly seen in the Asian population). When this happens, acetaldehyde accumulates, causing symptoms like rapid pulse, sweating, flushing, nausea and vomiting.
Heart
After a couple of drinks, some may experience a rapid or irregular heartbeat. Researchers aren’t entirely sure as to why this happens, but alcohol seems to directly affect our internal timekeeper. People who don’t drink regularly are more susceptible to this kind of reaction.
Circulatory System
Hot around the collar? Alcohol is what’s called a vasodilator, meaning it naturally enlarges the blood vessels, which can make your cheeks rosy and give you that warm and toasty “beer blanket” feeling.
Immune System
The immune system has two parts: One works to ward off sickness and the other fights off germs once they are already present. Because alcohol suppresses both, you are left not only more susceptible to illness, but also less able to fight it. This effect lingers for about 24 hours after throwing a few back.
Kidneys
The body normally releases a hormone called vasopressin, which, when alcohol is not present, sends water back into the body. But alcohol suppresses this hormone, and sends that water to the bladder instead, which, in turn, sends you to the bathroom line!
Bladder
In addition to the redirected water coming to the bladder from the kidneys, alcohol is also a natural diuretic, meaning it causes cells to shrink, thereby pushing water out from each cell. To manage that extra fluid, the organs secrete it to the bladder, which gives you the urge to go to the bathroom.
Although many people feel like after that first trip to the bathroom, the need to go only increases — a phenomenon often referred to as “breaking the seal” — this sensation is mostly an illusion. That “seal” is really just a threshold — after a number of drinks you can’t hold it any more. As you continue drinking, you’re taking in more fluids and suppressing the release of more vasopressin, leading to more frequent trips to the bathroom.
Libido
Because of the suppression happening in the frontal lobes, some people may find themselves feeling more in the mood for sex after a few drinks. But heavy drinking dulls sensation all over the body, making arousal and orgasm more difficult.
In addition, because alcohol naturally dilates the blood vessels, men may experience difficulty maintaining an erection at blood alcohol levels of about .08 to .10 and above. Blood still flows into the penis normally, but the dilated vessels allow it to flow out just as easily. While certain brain mechanisms might also affect this process, experts say there is little evidential proof.
Joints
Brain
Glutamate is a neurotransmitter with the opposite effect; it gets things going in the brain. But because alcohol can block the effects of glutamate at certain receptors, messages are further slowed in the brain.
Frontal Lobe
At blood alcohol levels of around .05, this area of the brain begins to show signs of disruption. This part of the brain is involved in decision-making and impulse control, so you begin to make poorer choices and may have more trouble controlling your urges.
As you move into a more moderate dose of alcohol consumption, you begin to only see the near future, called alcohol myopia, and the search for immediate gratification takes over. This is what causes you to eat a whole bunch of bar snacks when you’re on a diet, or kiss a cute stranger when someone special is waiting at home.
Ever told all your secrets while drinking? The more you throw back, the more you suppress the frontal lobes, until you eventually lose control over your emotional expression. The problem is, alcohol isn’t exactly a truth serum so your drunken confessions may not be what you really think.
Amygdala
This part of the brain warns you when you’re in danger. It makes you feel anxious and afraid when faced with a threat. With low doses of alcohol, the amygdala is slightly suppressed, so you begin to ignore the consequences of your actions (and you’re already making poorer choices because the frontal lobes are also suppressed).
As you move into a more moderate dose of alcohol, you can’t recognize when you’re in danger. This may account for risky sexual scenarios and any number of bar fights. It’s also what leads people to believe it’s a good idea to, say, jump off a roof into a swimming pool or other “Jackass”-style stunts.
Cerebellum
This part of the brain is important for memory, but is particularly involved in learning and executing patterns of movement. The more you drink, the more the cerebellum is disrupted, leading to balance problems, slower reaction time and slurred speech.
Reward System
Feel like having just one more? Our brains naturally make us feel good when we’re eating, having sex or engaging in other primal urges that are key to survival and reproduction to ensure that we repeat those behaviors. Because of its euphoric effects, alcohol tricks the brain into thinking that drinking is essential to our existence and we must continue, but the truth is it’s not.
Some people may be able to ignore this desire to raise another glass. Others, including possibly those who may be predisposed to alcohol dependence or abuse, might have an insatiable thirst for this euphoria and may be more inclined to continue drinking in order to hold onto it.
But that good feeling will only increase to a certain point. In fact, from the first sip of alcohol, the brain is working to return to homeostasis from its alcohol-altered state. If you’ve ever felt anxious or depressed as you begin to sober up it might be a type of rebound effect. You might feel worse the next day simply because you felt so great while getting buzzed and returning to normal can temporarily feel like a letdown.
Hippocampus
As you drink more, some impairment happens to the hippocampus, a part of the brain associated with memory. When you reach a blood alcohol level of about .15, the low end of the range considered a high dose of alcohol, you can start experiencing problems recording autobiographical memories, meaning you may not remember where you went or what you did. With a blood alcohol level of .2 or above, some research suggests there’s a 50 percent chance of experiencing this hole in memory, commonly referred to as a blackout. And when you wake up the next morning and a friend fills in the details, it’s not often good news, thanks to the suppressed frontal lobe and amygdala.
It can be difficult even for trained law enforcement to tell when someone has been drinking — or is experiencing a blackout — up until this .15 level. Drinking a higher dose results in a “sloppier” drunk; although it may still be difficult to tell if someone is experiencing a blackout, the physical impairments — like stumbling and slurred speech — will be obvious.
While many drinkers assume blacking out is a consequence of drinking too much, research suggests it’s more likely a result of how fast you drink, although experts are not exactly sure why.
Brain Stem
Deep down in the brain stem are a number of small circuits called the vital reflex centers. This is where sneezing, coughing, gagging, breathing and other involuntary reactions that keep us alive are controlled. If your blood alcohol level reaches .35 or higher, it’s possible to shut down these circuits completely. This is how alcohol overdose causes death, either directly, or, as is more common, by causing someone who vomits to inhale the vomit and drown.
Note: Certain prescription medications can affect the brain stem in a similar way, amplifying the risk of overdose. This is one of the reasons why many medications are not to be mixed with alcohol.
