To understand the next hangover theory, perhaps we should learn how ethanol is removed from the body. In a multi-step process, your body converts ethanol to carbon dioxide and water. The first step in this process is when an enzyme called alcohol dehydrogenase converts the ethanol to acetaldehyde. Next, your metabolic best friend, acetaldehyde dehydrogenase, converts this toxic acetaldehyde to harmless acetic acid. This process is not prefect, nor is it quick. These enzymes work at a constant rate, so removal of these toxic materials can take some time. A build up of acetaldehyde can cause symptoms of flushing, nausea and headaches.
The hangover is often blamed on the impurities within alcoholic beverages. These impurities are collectively called congeners. There is a bit of truth to this theory. Research has shown that “cleaner” spirits (gin or vodka) tend to produce fewer hangovers than “congener rich” spirits (whiskey, cognac or red wine). This theory was confirmed by researchers at the Center for Alcohol and Addiction Studies, Brown University, Providence, RI. In a study published in the March 2010 edition of journal Alcoholism:Clinical and Experimental Research, young drinkers either received bourbon or vodka to the point of intoxication. On the morning following bourbon consumption, subjects felt their hangover was more severe compared to the mornings after they drank vodka.
Craft beer lovers crave congeners; these impurities are responsible for flavor, smell and appearance. In smaller amounts, congeners give beer and other alcoholics beverages their characteristic flavors. Too much and you will have a difficult time clearing them from your body. The problem may not the congeners themselves, but how your body processes them. The enzymes that breakdown ethanol, also breakdown other forms of alcohol in your pint glass. Perhaps the most notorious congener is methanol, which is more of a concern for distilled spirits. Alcohol dehydrogenase converts methanol to formaldehyde. The symptoms of methanol ingestion mimic hangover symptoms perfectly. Heaven only knows what these enzymes produce from the fusel alcohols, esters and phenolics present in beer. Not all morning-after woes can be blamed on congeners; pure ethanol can still cause a hangover.
Low blood sugar is another theorized cause of hangover symptoms. It is true that symptoms of low blood sugar mimic hangover complaints: hunger, weakness, sweating, trembling and confusion. In reality, low blood sugar from alcohol consumption only occurs under certain circumstances: chronic alcoholism, low carbohydrate diets or not eating enough. Alcohol can deplete glycogen (energy) stores in the liver, but this generally takes several days to occur. People with diabetes are more sensitive to alcohol-induced changes in blood sugar.
Lack of sleep is also thought to contribute to hangover symptoms. While alcohol can act as a mild sedative, quality of sleep is affected. Time spent in the restful rapid eye movement (REM) sleep is reduced with alcohol intoxication. Alcohol relaxes throat muscles, which may cause snoring and possibly sleep apnea. Imbibing can also reduce the body’s production of melatonin, which is required for a restful sleep. While it is true that beer does contain melatonin, its presence is minor and not thought to be significant enough to help with sleeping. Pair this with any other sleep disturbances and you have one tired beer geek. Let’s not forget that alcohol is a diuretic; frequent nighttime trips to the bathroom won’t help matters. Are symptoms of sleep deprivation similar to a hangover: muscle aches, depression, headaches, nausea, fatigue, memory lapses and irritability. Sounds right to me.
“There is extensive literature on the effects of alcohol on sleep,” explains Dr. Jonathan Howland Professor of Community Health Services at Boston University. “Alcohol can affect sleep architecture and breathing (apnea) and both these effects can disturb sleep. He points to research that appeared in the May 2011 issue of the journal Alcoholism: Clinical Experimental Research. In this study researchers gave healthy adults sufficient bourbon or vodka to reach a breath blood alcohol concentration of 0.11g percent. After being tucked in for the night, researchers followed the imbibers sleep patterns. What they found was that subjects fell asleep faster, but their sleep was not as restful. They experienced less REM sleep, greater wakefulness and more slow wave sleep. He further explains, “The connection we investigated had more to do with heavy drinking effects on next-day performance rather than on hangover, but fatigue is associated with hangover.”