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What you don't know about alcohol

Why are we thirsty the day after a night out?

Our body is dehydrated.

In addition to mobilizing our body's water reserves, Allen C.D. has shown that alcohol disrupts the functioning of the brain's pituitary gland, leading to a decrease in the secretion of the antidiuretic hormone.

This hormone is involved in the reabsorption of water by the body in the kidney.

Simply put, the body eliminates more water than it absorbs. The person then experiences dehydration symptoms, such as fatigue and especially headaches. Don't wait until you're thirsty to rehydrate, as it will be too late.

Why do we have a headache?

Several reasons are related to headaches caused by alcohol consumption.

The first reason, as we've already discussed, is that alcohol causes severe dehydration.

The second reason is that the sugar present in alcohol encourages the body to produce insulin, causing our blood sugar to drop. Hypoglycemia induces headaches.

The third reason is the accumulation of acetaldehyde, a toxic metabolite of alcohol. Acetaldehyde is an intermediate product generated in the liver during the alcohol elimination process. It is also responsible for hangover symptoms such as headaches.

Although alcohol is considered a sedative, its consumption disrupts our sleep.

Alcohol binds to many receptors in the central nervous system such as GABAA receptors (the most important inhibitory neurotransmitter in the human brain). Consequently, excessive consumption has a depressant effect on the central nervous system, and this influences sleep in several ways:

Thakkar M.M. et al., (2015), showed that alcohol affects sleep in several ways:

  • Disturbance of the sleep cycle
  • Reduction of REM sleep and disruption of slow-wave sleep
  • Nighttime awakenings
  • Exacerbation of certain sleep disorders (snoring or sleep apnea)

Sleep quality is thus affected by alcohol consumption.*

Why are we tired?

Fatigue is explained by a combination of 3 factors:

1/ lack of sleep
2/ dehydration
3/ energy expenditure generated by the body to eliminate the toxic element (alcohol)

Why do we crave fatty foods?

Two reasons are behind this behavior:

  • Costardi J.V. et al., (1992), showed that alcohol activates the endocannabinoid system receptors that cause hedonic hunger. That is, hunger not justified by a need, with an attraction to foods that will give us pleasure, often fatty and/or sweet. (this phenomenon is also found after cannabis consumption) **

  • When consuming alcohol, the inhibition threshold in our brain is lifted. That is, we give free rein to our emotions, our desires, without considering the consequences and the context. Biologically, the disinhibitory effect of alcohol can be explained by the inhibition of two neurotransmitters: norepinephrine and serotonin. As we've already discussed, by binding to GABA receptors, alcohol exerts an inhibitory activity. Here, on norepinephrine and serotonin, disrupting their secretion.

- Norepinephrine controls our reactions to danger.

- Serotonin contributes to the control of emotion and mood.

Cains S. et al., (2017), showed that alcohol had an effect on the hypothalamus, especially on Agrp neurons. These neurons are involved in regulating the sensation of hunger, and alcohol's action on them decreases our sense of satiety.

Normally, it helps control our appetite and our cravings for calorie-rich foods. But after a few drinks, the satiety barrier is lifted. ***

Is there a type of alcohol to avoid?

A 2009 study by Brown University showed that dark alcohols contained more impurities than clear ones. Gin, vodka, sake vs red wine, beer, whiskey

These impurities are associated with more pronounced hangover symptoms.

It is also necessary to choose a quality product because the quality of alcohol plays an essential role. For example, poorly distilled spirits will contain other types of alcohol such as methanol, which can be dangerous in high doses.

Why is alcohol eliminated differently from one person to another?

Regardless of the quantity consumed, the liver can only metabolize a certain amount of alcohol over time. This process quickly saturates, and the rate of metabolism depends on the amount of metabolizing enzymes (cytochromes) present in the liver. An interindividual factor defines this quantity, which varies from person to person and seems to be genetically determined.

Allen, C. D., (2011). Immediate and prolonged effects of alcohol exposure on the activity of the hypothalamic–pituitary–adrenal axis in adult and adolescent rats. Brain, Behavior, and Immunity, 25, S50‑S60. https://doi.org/10.1016/j.bbi.2011.01.016

Cains, S., (2017). Agrp neuron activity is required for alcohol-induced overeating. Nature Communications, 8(1). https://doi.org/10.1038/ncomms14014

Costardi, J. V. V., (2015). A review on alcohol: from the central action mechanism to chemical dependency. Revista da Associação Médica Brasileira, 61(4), 381‑387. https://doi.org/10.1590/1806-9282.61.04.381

Thakkar, M. et al., (2015). Alcohol disrupts sleep homeostasis. Alcohol, 49(4), 299‑310. https://doi.org/10.1016/j.alcohol.2014.07.019

* https://www.educalcool.qc.ca/wp-content/uploads/2019/09/Alcool-et-sommeil.pdf

** According to a study published in the journal Sleep

*** A second study, published in the journal Health Psychology,


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