Emily Stearn, health reporter for Mailonline
09:14 05 July 2024, updated 09:32 05 July 2024
Chances are you consider yourself a moderate drinker.
Maybe it’s that special bottle of wine in the evening after work. Or a few pints with friends in the pub.
But while some of the dangers associated with excessive drinking are obvious, others can appear much more subtle.
Leading experts have debated the harms of moderate drinking for decades.
The NHS advises people to drink no more than 14 ‘units’ of alcohol – around six glasses of wine or pints of beer – a week.
That itself has been weakened over the past few decades in light of studies illustrating the health dangers of alcohol.
So how do you know when your drinking has slipped into something more harmful? We ask the experts…
Feeling tired all the time
Experts say that pouring yourself a glass before hitting the sack will only leave you groggy, dehydrated and potentially battling a pounding head.
Booze interrupts the rapid eye movement (REM) phase of sleep. This stage—the deepest of the four that we all go through each night—is vital for memory, learning, and creativity.
Ian Hamilton, who specializes in addiction at the University of York, said this part “provides rest and regeneration for the brain”. This is why you may wake up at night after drinking, which can make you feel less refreshed.
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Dr Melissa Oldham, from the University College London (UCL) Tobacco and Alcohol Research Group, explains that this is because the body metabolizes alcohol later at night.
After drinking, people may nod off more quickly due to alcohol’s sedative effect, which can increase relaxation and sleepiness.
But after alcohol is absorbed into the bloodstream from the stomach and small intestine, it is metabolized slowly throughout the night.
“This can lead to people waking up more often and feeling more tired the next morning,” she said.
But it’s not just a lack of REM sleep that makes you feel groggy — the dehydrating effects of alcohol will also make you feel tired the next day, experts say.
It can cause drinkers to wake up in the night needing water, as well as needing to go to the toilet.
Long-term alcohol use also impairs the absorption of B vitamins and folate, which are essential for healthy red blood cells.
‘Excess alcohol [can cause] macrocytic anemia, where red blood cells are enlarged but ineffective and break down faster than healthy red blood cells,” says Dr. McLaughlan.
“Symptoms can include fatigue, loss of balance, tingling, mood disturbances and stomach upset.”
Sexual desire changes
Experts have long warned that excessive drinking over a long period of time can lead to a decrease in sexual desire, or libido.
Alcohol can initially have a reinforcing effect on hormones such as serotonin, dopamine and testosterone, which can seemingly increase our sex drive.
“However, over time these levels decrease, reducing the amount of sexual desire a person experiences and could potentially lead to depression or anxiety,” adds Penman.
According to Drink Aware, in men, alcohol depresses the central nervous system, which means some men may find it difficult to achieve and maintain an erection.
Drinking can also prevent or delay orgasm, and over a long period of time can even turn a temporary condition into long-term impotence.
Like men, women may have difficulty achieving orgasm or may have orgasms that are less intense after drinking alcohol.
Low mood and anxiety
Alcohol is a depressant that can initially produce a calming effect.
However, as Lisa Gunn, head of mental health prevention at Nuffield Health, explains: “When it wears off, we usually see a rebound effect where anxiety levels go up.
“This is partly because alcohol disrupts the balance of neurotransmitters and chemical messengers in the brain.
“There is also a social aspect to this. When we drink, we become drunk and “carefree,” which can cause us to say and do things we wouldn’t do sober.
If we blackout (a period of alcohol-induced memory loss) during a period of acute intoxication, we are even more likely to wake up with feelings of anxiety, fear, apprehension and dread.”
Vision problems
Dizziness, blurred vision, or even double vision are common temporary effects of drinking booze.
But drinking can also cause “dry eye symptoms”, says Stephen Hannan, director of clinical services at Optical Express.
“This can include red eyes due to swelling of the blood vessels in the eyes, otherwise known as a bloodshot look, itching, irritation or discomfort, and fluctuating vision.”
“Although these are only minor problems, long-term alcohol abuse can actually permanently damage the optic nerves in our eyes, the connections responsible for sending visual information from the eyes to the brain,” he adds.
Research has linked alcoholism to an increased risk of developing macular degeneration — a condition that affects the middle part of your vision — and optic neuropathy, where blood flow to the eye’s optic nerve is impaired.
The exact relationship between alcohol abuse and these diseases is not known, but researchers suggest that it may be due to vitamin A deficiency, which is often associated with alcoholism.
“Eliminating or drinking less alcohol will allow your body to reverse over time and slow down many of the short-term and long-term effects of drinking,” says Hannan.
“For example, after just 24 hours without alcohol, blood sugar levels return to normal and blurred vision caused by alcohol consumption disappears.”
Weakened immune system
Our immune system helps keep us healthy.
However, drinking can weaken this system and leave us vulnerable to infection and disease.
Carolina Goncalves, senior pharmacist at Pharmica, says: “Short-term alcohol consumption can inhibit the activity of immune cells such as macrophages, T-cells and B-cells, which are essential for identifying and fighting pathogens.
“This damage increases the body’s susceptibility to infection and disease.
“Additionally, alcohol directly affects the gastrointestinal system, the first point of contact before entering the bloodstream.
“The gut microbiome, the community of microorganisms that aid gut function and immune system maturation, is affected by alcohol.”
He adds: “Research shows that alcohol disrupts communication between gut microbes and the gut immune system.
It also damages epithelial cells, T-cells, and neutrophils in the GI tract, disrupting the gut barrier and allowing microbes to leak into the bloodstream.
“Finally, alcohol can affect the production of cytokines — proteins that control inflammation — leading to an unbalanced immune response.”
Changes in your menstrual cycle
Studies also suggest that heavy drinking can wreak havoc on your menstrual health.
Ms Goncalves says: “Further research has found that the ethanol in alcohol can disrupt the interaction of the hormone-producing pituitary gland with the hypothalamus, the area of the brain responsible for emotional regulation, and the ovaries.
“These interactions are collectively referred to as the ‘hypothalamic-pituitary-gonadal (HPG) axis.’
“Alcohol consumption can disrupt the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are part of the HPG axis.
“This can affect the maturation of ovarian follicles and the way ovulation is triggered, resulting in hormonal and physiological changes that can cause irregularities in menstrual cycles.”
Fertility problems
According to the British Fertility Society, drinking can also reduce women’s fertility.
It causes an imbalance in the hormones that control reproduction, and even in small amounts it can affect a woman’s menstruation and reduce the chance of conception.
Britain’s chief medical officer recommends that women who are trying to have a baby or pregnant women should not drink alcohol at all to minimize the health risks to the baby.
One Danish study showed that drinking one to five drinks a week can reduce a woman’s chance of conceiving, and 10 or more drinks reduces the chance of conceiving even more.
Evidence also suggests that drinking more than 14 units per week reduces testosterone levels and the quality and quantity of sperm in men.
This is because men who regularly exceed the guidelines are at risk of destroying the sperm-producing cells in the testicles, which will affect the quality of their semen.
Dr David McLaughlan, Consultant Addiction Psychiatrist at Priory Hospital Roehampton, also says: ‘Excess alcohol reduces testosterone production in men, as well as disrupting other hormones, which in turn affects the number and quality of sperm produced by men.
“In women, alcohol interferes with ovulation and implantation of a fertilized egg.”
High blood pressure
Indulging in a drop can also affect blood vessels.
“That can cause it to narrow. When your blood vessels are narrower, the heart has to work harder to push blood around your body and raise your blood pressure,” says Nathan Penman, clinical manager at Nuffield Health.
In addition, high blood pressure, or hypertension, puts a strain on organs including blood vessels, the heart and the brain, and can increase the risk of heart attack, stroke and dementia.
The condition, which affects around one in four adults in the UK, does not usually trigger symptoms.
However, those with very high readings may experience headaches, blurred or double vision, regular nosebleeds, or shortness of breath.