September 24, 2021

I, Science

The science magazine of Imperial College

Katie Tomlinson & Jan Piotrowski explore the science of drinking. From the night before to the morning after, here is the science behind a great night out.

Meet Ruth. She’s getting ready for a big night out, all in the name of science. Whilst she’s drinking we’ll be thinking…



20:30 – “Just arrived at Stu’s house for a couple of sneaky drinks to wet my whistle before hitting the pub.”

Before heading out for a night on the town, many of us indulge in some rapid pace, high stamina drinking. During these drinking sessions, alcohol is absorbed very quickly through the lining of the stomach and circulates around the body. Alcohol really does go straight to the head, as only six minutes after consuming alcohol brain cells undergo some distinct changes. The walls of neurones are composed of two barriers, separated by a layer fat that enables electrical signals to be conducted. Alcohol destabilises neurone walls, and reduces the concentration of protec­tive substances such as creatine, and in turn prevents electrical signals being sent as normal. Whilst drugs such as cocaine and morphine act at highly specific receptor sites, alcohol is as precise as a hand grenade, affecting a huge variety of neurotransmitters. This produces a wide range of effects, and can explain why everyone reacts to alcohol in a slightly different way.

22:00 – “Queueing at the bar, getting the first round in. Hope the barman’s quick because I’m bursting!”

Normally, the amount of water in the blood is tightly regulated by the pituitary gland, which produces the hormone vasopressin. Vasopressin increases the permeability of kidney tubules and allows re-absorption of water. Alcohol inhibits the production of vaso­pressin, resulting in decreased re-absorption of water and causing large volumes of water to be lost in urine.Unfortunately, this also leads to a loss of four times more liquid than is gained and causes dehydration. Urination may be induced 20 minutes after alcohol consumption, prompting us to ‘break the seal’.

“Right. Bladder Empty. Now for the dancefloor.”

Listening to music elicits strong activation in areas of the brain associated with reward and motivation. Responses to other survival-related stimuli such as food, sex and drugs show similar patterns in brain circuitry. Recruitment of the reward centre suggests that music may have once been important for sur­vival, facilitating the social cohesion of large groups. Even young babies appear to innately possess the perceptual skills necessary to appreciate music, strengthening the case for the evolutionary importance of music. The basal ganglia is an area of the brain heavily involved in processing rhythm, making it es­sential for co-ordinated dancing. However, alcohol inhibits activity in this area, leading to increasingly cringe-worthy dancing.

01:38 – “Just caught a boy giving me the eye – I’m going to make a move.”

Flirting strongly activates the limbic system, which is responsible for regulating the brain’s emotional responses. Functional MRI studies have shown that whilst flirting, the limbic sys­tem bypasses the more rational neo-cortex, in a way that prevents decision making in brain damaged patients. Dr Antonio Darmasio, MD and head of neurology at the University of Iowa believes that by blocking rational decision making, nature is making sure that it is only sexual attraction that has a say.

Studies have shown that women are attracted to androstenol, a pheromone released in male sweat. However, androstenol is only attractive when fresh, so don’t give up on laundry day just yet. Interestingly, this pheromone is also secreted by truffles, justifying long standing claims of their aphrodisiac qualities. Humans are also unconsciously attracted by smell to mates whose major histocompatability complexes (MHC) differs from their own. MHC are genes related to the immune system; so this behaviour evolved to increase genetic diversity and surival within a population.

02:22 – “Some slapper just moved in on my boy, and knocked over my drink. What is her problem?”

Alcohol may encourage aggression by disrupting normal brain function in a number of ways. Alcohol weakens brain activity involved in restraining impulsive behaviour, making us less inhibited. Whilst we also experience a disruption in information processing, which can lead to misinterpretation of facial expressions. Anxiety levels are also reduced when drinking, which makes us less willing to avoid dan­gerous situations. In addition, the dark, crowded, loud drinking pub/club environment has been shown to cause frustration. When combined, these factors make us less able to assess the situation and more likely to give in to violent impulses.

04:15 – “Why am I here on the sofa? How the hell did I get home?”

Familiar with feelings of shame, despite a complete lack of memory? Memory loss from drinking can be caused by the GABA signalling system in the brain, which in­hibits brain activity. The conversion from short to long term memories is disrupted as the inhibition acts particularly strongly on the hippocampus, the part of the brain re­sponsible for forming and consolidating memory. The breakdown of alcohol creates a by-product of ethyl esters, disrupting the balance of positive charge within neurons. Coupled with a decreased level of oxygen in the brain, this also acts to disrupt the function of the hippocampus. Blackouts are often caused by rapid drinking on an empty stomach, leading to high alcohol concentration in the blood.

Beer Goggles

Alcohol is well known for skewing the perception of attractiveness of potential partners, and reducing sexual inhibitions. Researchers at Manchester have quantified this ‘beer goggles’ effect with a complex formula.

  • An = number of units of alcohol consumed
  • S = smokiness of the room (graded from 0-10, where 0 clear air; 10 extremely smoky)
  • L = luminance of ‘person of interest’ (candelas per square metre)
  • Vo = Snellen visual acuity (6/6 normal; 6/12 just meets driving standard)
  • δ = distance from ‘person of interest’ (metres; 0.5 to 3 metres)

Booze and neurotransmitters

  1. Glutamate – Alcohol inhibits glutamate re­ceptor function, meaning you might suffer malcoordination, slurred speech, staggering, memory disruption, and black­outs.
  2. Gamma-aminobutyric acid (GABA) – Alcohol enhances GABA recep­tor function, providing feelings of calm, anxiety-reduction and tendency to sleep.
  3. Dopamine – Alcohol raises dopamine levels, explaining drunken excitement and heightened stimulation.
  4. Endorphins – Alcohol raises endorphin levels. Hence, you become happy and drunken falls aren’t painful.