By Craig Gunn – PhD student, University of Bath
We’ve all been there – the headache, the fatigue, and the sickness – the inevitable hangover that follows after heavy alcohol consumption on a night out.
Trying to work the next day, if we even feel up to going in, can be near-impossible, and even driving to get there can feel unsafe. With vast implications for public safety, the economy and the workplace, understanding how a hangover effects cognition and behaviour is vitally important. However, studying the next-day effects of a night of heavy drinking is not as straightforward as it may seem.
An experimentally induced hangover
Studies that explore the cognitive effects of acute alcohol intoxication use the ‘gold-standard’ double-blind, placebo-controlled experimental approach. In these studies, participants receive either alcohol (usually vodka and orange), or a placebo (orange juice with a small amount of vodka ‘floated’ on top). Both the researcher and the participant are not aware of which drink is being consumed until the end of the study. This manipulation is intended to prevent participant’s expectancy about alcohol (e.g. feelings of relaxation) and the bias of the experimenter influencing the effects of alcohol on the measured outcome.
During these studies, the amount of alcohol given to each participant is controlled so that individuals reach a similar blood alcohol concentration. Studies are typically conducted in the laboratory where other variables that may influence performance are controlled, such as noise. This model can also be applied to studies of alcohol hangover. A set dose of alcohol can be administered in an evening using the double-blind placebo controlled method, and participants can either go home and return the next morning or sleep in the laboratory (if facilities are available).
Unfortunately, there is a problem with this approach when studying the effects of alcohol hangover. The condition assigned (alcohol or placebo) is readily guessed by participants, and the large amounts of alcohol needed to induce a hangover, may leave ethics committees feeling uneasy. For example, in studies of acute alcohol intoxication a ‘high dose’ of alcohol which is usually approved by ethics committees is around 2.5 pints of a 5% ABV lager consumed within 30 minutes. However, to replicate the levels of drinking typically seen prior to experience of a hangover, participants would need to drink the equivalent of 4.5 pints in 30 minutes.
A naturally induced hangover
Perhaps unsurprisingly, the higher the amount of alcohol an individual consumes, the more likely they are to report having a hangover the next morning. Higher levels of alcohol consumption are associated with greater reports of hangover severity and poorer performance on tests of attention. The association between levels of alcohol consumption and performance on cognitive tests during hangover has created a lot of debate between researchers on how to conduct hangover studies. Clearly the dose of alcohol is important, and higher doses in studies may increase the likelihood of cognitive impairment being detected during hangover. In order to effectively measure cognition the morning after a night of heavy drinking, participants may need to consume higher amounts of alcohol than are possible in an experimental model of hangover induction. To address this, some researchers have adopted a ‘naturalistic’ method, which asks participants to attend a test session the morning after a night where they had planned to go out drinking, and participants are free to drink the amount and type of alcohol they normally would. This approach has enabled researchers to explore hangover effects after participants have consumed more alcohol than has been possible using an experimental approach (around 5 pints compared to 2.5 pints).
The naturalistic method is not without its criticism. Although higher doses of alcohol are consumed which may make this approach more sensitive to measuring hangover effects, the lack of control (i.e. placebo) makes it difficult to discover the mechanisms underlying the cognitive effects of hangover. Another line of research suggests that the type of beverage consumed may be important when considering the next-day effects of alcohol. Unlike the experimental method, the naturalistic approach does not allow the type of drink consumed to be controlled for (e.g. vodka). In real-life drinking situations people often mix drinks. This is potentially problematic as different drinks have different congener content (e.g. dark drinks such as red wine have a larger amount of congeners than lighter coloured drinks such as gin). Congeners are bi-products of the alcohol fermentation process, such as methanol, which have implicated to be important in the development of hangover. Similarly, it is not possible to control for differences in activity in the naturalistic method, and physical activity, such as dancing, may influence cognitive abilities during hangover. Another factor which is known to impact performance is sleep, and in real-life situations it is not uncommon that sleep time is sacrificed for drinking time.
The future of inducing a hangover
Some of these criticisms could be addressed with the use of wearable technologies, where sleep and activity could be monitored. However, a hangover consists of a combination of symptoms (e.g. nausea, anxiety etc.), which may be influenced by many complex and interacting mechanisms. Therefore, an approach which incorporates and examines a range of contributory factors (e.g. mixing drinks, physical activity) may be needed to understand the influence of hangover on cognition and behaviour. For this, the naturalistic approach is ideal. With improvements in hangover research methodology, greater understanding of the mechanisms which underlie hangover effects can be achieved, which in turn could improve public safety, workplace dynamics, and the economy.
Exploration of how hangover effects our thoughts and behaviours is a fascinating area of research with vast implications for everyday life, such as work performance and driving. Researchers are now beginning to use a range of methods to unravel the effect hangover has on our attention, memory and psychomotor abilities, and the development of more robust and relevant methodology to study this field will only strengthen the validity of results.