For many the festive period is a time that is filled with drunken nights out that often result in anxiety the next morning.

That feeling of anxiety, not remembering what happened, and of regret after drinking alcohol is a real phenomenon, and can be described as 'beer fear', or 'hangxiety'.

Now, Liz Burns is a lecturer of mental health nursing at Salford University with a specialism in alcohol services, has lifted the lid on what happens when we drink booze and have these feelings after a night out.

She told the Manchester Evening News : "Alcohol forces the brain to switch off the central nervous system because it is a depressant rather than a stimulant drug.

"Our inhibitions are turned off which is makes us feel relaxed and confident. 

"Because alcohol is a depressant, our motor coordination becomes slower, which is why we may become clumsy.

"As brain processes slow down, your memory can become impaired."

For many, the festive period is a time for nights out

Liz explained the liver is the only way alcohol can be broken down and metabolised.

She said: "It can break down one unit per hour, so if you're drinking above this, your blood alcohol level increases.

"A glass of wine for example has 3.5 units.

"When blood alcohol levels increase with the more we drink, the more 'switching off effect' we experience.

"The more we drink, the faster our liver has to work to break down the alcohol and when it exceeds this rate, that is when we become intoxicated.

"But drinking so much in a single episode can be very dangerous.

"It can result in alcohol poisoning and in some instances, the body can become unconsious."

But why does it happen? Some may call it the 'beer fear', while others describe it as 'hangxiety'.

Two Christmas revellers lay on the ground in Swansea

Why might we feel anxious and have 'the fear' the next morning?

Liz, who is  chairman of research project Communities in Charge of Alcohol (CICA), said: "Feeling anxious the next day is down to the interaction of chemical compound glutamate.

"We may feel fearful because we can't remember everything that happened the night before; it's not at the forefront of the mind.

"We may be able to piece together moments, and memories can sometimes come back to us when we're stimulated by something."

Drink Aware, an independent alcohol advice charity, said that after drinking large quantities of alcohol, the brain can stop recording into the 'memory store'. 

An explainer on their website says: "That's why you can wake up the next day with a 'blank' about what you said or did and even where you were.

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"This short-term memory failure or 'black out' doesn't mean that brain cells have been damaged, but frequent heavy sessions can damage the brain because of alcohol's effect on brain chemistry and processes."

Liz added: "Alcohol makes it also impossible to have a deep sleep as it disrupts it, which isn't good for mental wellbeing.

"However someone may think they slept because they had their eyes shut, but the liver is working overnight to break down the alcohol so it's not a restful sleep and affects the quality.

"It's neither deep and makes you out of sorts."

She said: "In the longer term, mood problems may occur as people might drink to feel better - but it's a vicious cycle.

"Feelings of anxiety may initially feel better with drink. Others may have a 'night cap' to send them off to sleep, but it'll actually cause disruption and they'll be awake earlier."

Liz's advice is low-risk drinking over binge-drinking, which can be followed by using the limit of 14 units a week, to be spread out across the seven days.

Why do we crave junk food on a hangover?

"The day after drinking, the body will turn back on and try to re-balance after being switched off", said Liz.

She continued: "When you drink alcohol, because it is so high in sugar, when you stop, the next morning, your blood sugar levels are likely to have dropped to re-balance the body.

"Along with being dehydrated, the body craves carbohydrates, which is why some may want junk food to re-align.

"The body is trying to compensate."

Alcohol dependency

"Extra caution is needed if you have developed an alcohol dependency - which includes feelings of anxiety and other symptoms as withdrawals, such as having a mild tremor or shake, or find yourself sweating", said Liz.

"Some consumers can have a psychological dependency, where they think about alcohol and feel better after a drink.

"If you're drinking every other day, with only so many hours without, withdrawal affects can create a complex rebound excitation; to the extent of seizures and fits. And if severe, these can be life threatening."

Liz added: "What's worse is the more you drink, the higher your tolerance will develop." 

If you think you may have an alcohol dependency, then you can speak to a local alcohol service who can check your dependency and help you from there.

Advice and information on alcohol can be found on the NHS website .

You can also receive a personalised plan by answering five questions with the  Every Mind Matters NHS campaign .