Debunking the Myths Behind the Alcohol Hangover

Many of us are probably all too familiar with the looming dread that comes with the morning after a night of drinking. That limbo-like existence where you are too tired to get up...
27 February 2017


Many of us are probably all too familiar with the looming dread that comes with the morning after a night of drinking...

That limbo-like existence where you are too tired to get up and face the routines of everyday life, while your mind is too overactive to allow you to fall back asleep. The feeling of deep-pitted hunger that is accompanied with an over-sensitive gag reflex at the thought of sitting down for breakfast. The mouth-drying thirst and the throbbing headache. You are experiencing the effects of the infamous alcohol hangover - certain to come along as an extra treat for those of us who are determined to let our carefree sides reign for the night.

The alcohol hangover, better known in the scientific communities as ‘veisalgia’, refers to the morning after a night of heavy alcohol consumption, where blood alcohol concentrations return to zero, leaving us to deal with a variety of generally awful symptoms such as drowsiness, dry mouth, nausea, concentration problems, anxiety and much more. The reason that veisalgia is still discussed in scientific communities is because scientists have so far been unable to narrow down its definite causes or come up with a cure. It is an over-simplification to just say that excessive consumption of alcohol causes hangovers, because while some of us can get away with heavy drinking without experiencing any pain the day after, others suffer through bad hangovers after drinking relatively little. Another question of interest regarding hangovers is why we experience all these symptoms even after alcohol has been fully expelled from our bodies – even when our blood alcohol concentration has dropped all the way back down to zero.

One widespread belief, that has not been firmly proven, is that dehydration causes alcohol hangovers. The logic behind considering dehydration as the main cause is not unreasonable – as a diuretic, alcohol increases the production of urine in the body, leading to dehydration, which in turn conceivably causes hangover symptoms like thirst and dry mouth. However, scientists have monitored key indicators of dehydration - such as the levels of a hormone called vasopressin - which tells a different story.

Vasopressin is an antidiuretic hormone, which is important in regulating the body’s water balance. When there is a lack of body water, the vasopressin hormone is secreted and the body consequently attempts to conserve water. Higher levels of vasopressin in the body therefore indicate dehydration. Interestingly, studies of vasopressin levels show that there is not a strong enough correlation between dehydration and the severity of hangover symptoms. There is more evidence to suggest that other factors, related to the body’s immune system, cause the more cognitive hangover effects such as memory impairment. It seems that hangovers and dehydration can be better interpreted as two independent but coinciding factors, with different underlying mechanisms. A fair warning though – this does not mean that you should now give up drinking water after a night out. Dehydration does occur when you drink heavily, so staying hydrated is still necessary to prevent headaches the next day. However, other hangover symptoms are unlikely to be prevented by attempts at staying hydrated. Scientifically speaking, it seems to be incomplete, and to some level inaccurate, to identify dehydration as the main cause of alcohol hangovers.

Sleep disturbance
Another commonly hypothesised cause of alcohol hangovers involves sleep disturbance. When you drink heavily, you may notice that you wake up frequently in the night, and maybe even experience more vivid dreams. Studies with EEG monitoring that measure sleeping brainwave patterns explain that alcohol consumption affects our REM (rapid eye movement) sleep, which is the stage where dreaming and learning occur. Scientists have found that while just one or two drinks may not affect REM sleep, excessive drinking does, leading to more superficial and disturbed sleep, which inevitably causes hangover symptoms like tiredness and difficulty concentrating the next day.

Clearly, there is a link between the amount of alcohol consumed and sleep disturbance. However, it is important to see that while many people complain of hangovers after heavy drinking, many of these symptoms are directly due to a lack of sleep and not the amount of alcohol they have consumed. This is further apparent when you consider the fact that the longer a person is out drinking, the less time they probably leave for sleep. It again appears that sleep disturbance is another factor, a bit like dehydration, that co-occurs with hangovers because of heavy drinking, leading to some shared symptoms such as tiredness, rather than explaining the scientific mechanisms behind hangovers themselves.

Low blood sugar
Other popular theories attribute hangover symptoms to low blood sugar, or hypoglycaemia. The normal way that we get useable energy from the simple sugar glucose in our food is through a process called glycolysis. This process is fundamental in allowing cells to respire and allowing us to live. However, during longer periods of time where we do not eat, like when we are sleeping, a reverse process takes place – gluconeogenesis – where the body converts non-carbohydrate sources into glucose in the liver, so that we don’t lose all our energy after a long night’s sleep. Alcohol consumption effectively inhibits gluconeogenesis, leading to lower levels of glucose or low blood sugar. In effect, a lot of the hunger pangs and lack of energy that we experience after a night of drinking can be traced back to this phenomenon. However, some researchers argue that this effect is not as significant for people who have normal glycogen stores, as glycogen continues to break down into glucose despite heavy alcohol consumption, raising blood sugar levels back up. So, perhaps suggestions to drink sugary sports beverages to aid a hangover do not actually address the source of the problem.

There are many other possible causes that can be put forward to explain hangovers, but these seem to only address some hangover symptoms and not all the symptoms collectively. For instance, the nausea and vomiting experienced during a hangover can be ascribed to gastritis, or the inflammation of the stomach lining. Moreover, both increased urination and vomiting as a result of drinking can lead to the body losing a lot of potassium – which could exacerbate hangover symptoms like tiredness. But these reasons cannot explain the underlying mechanisms that cause many symptoms to occur even when alcohol has been expelled from the body.

A more promising theory, put forward by the ‘Alcohol Hangover Research Group’, is that hangovers are like an inflammatory response caused by our body’s immune system. The immune system is the body’s natural defence against infection and disease. When an infection or disease attacks our immune system, there is an increase in the level of a family of molecules called cytokines. These are inflammatory hormones that prime the immune response to fight infections. The relevance of cytokines to hangovers is that when cytokine concentrations increase, the effects on the body are much like the symptoms of an alcohol hangover, indicating that their fundamental mechanisms might be similar. The presence of cytokines leads to sickness behaviour, producing symptoms like weakness, inability to concentrate and sleepiness, all of which are also experienced during a hangover.

In addition to the above, relatively newer research also points to the relationship between the body’s immune system and hangovers, particularly the finding that the immune system and the central nervous system (consisting of the brain and spinal cord) appear to communicate closely with each other. Importantly, scientists have found high densities of cytokine receptors, which detect signals from these molecules, in a part of the brain related to memory function. During a hangover, many people report having trouble remembering things from the night before. In a very similar way, increased cytokine levels have been found to cause significant memory impairment. Together these observations suggest a relationship between the immune system and the hangover, and highlights why anti-inflammatory drugs like aspirin can soothe an alcohol-sore head.

There is also another noteworthy explanation of hangovers which relates to the metabolism or processing of alcohol in the liver. Liver cells are largely responsible for the metabolising of alcohol molecules. They contain enzymes that break apart alcohol molecules in different stages, ultimately resulting in the breakdown of alcohol to water and CO2, which can be passed out in urine and air from our lungs. However, the first stage of the metabolising process results in the production of a toxic chemical, called acetaldehyde. While this chemical is short-lived, before undergoing another metabolic reaction, it can still do a lot of damage to the body in a short time. In fact, researchers believe that many behavioural and psychological effects of hangovers can be attributed to this chemical - a claim that is supported by experiments where the chemical itself was given to lab animals and resulted in symptoms like incoordination, memory impairment and sleepiness, i.e. the common hangover effects. It is also interesting to note that alcohol metabolism is different for all individuals, controlled by both genetic and environmental factors, which could explain why we all experience different levels of hangover severity even if we consume similar amounts of alcohol.

Just drink sensibly
So the alcohol hangover is undoubtedly a confusing phenomenon. While there appears to be some forward direction in finding what causes hangovers and why, the exact causes are still a grey area, which explains why we can’t just take a miracle pill to help us feel better after drinking a lot. To make things more complicated, there are also links between the flavour or colour in drinks and hangover severity, which explains why fewer drinks of wine can produce as severe a hangover as several pints of beer. Moreover, the co-occurring effects of dehydration and sleep disturbance after heavy drinking lead to a whole range of shared symptoms with the alcohol hangover, making it difficult to separate all the underlying processes. Other researchers suggest that there is potential for making drinks with a synthetic substance other than alcohol that still can make a person tipsy, but for now, it appears that we will just have to endure the pain of hangovers with aspirin, water and lots of rest - or just drink sensibly instead!


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