Many of us feel sluggish the morning after a heavy evening of festive boozing, but we want to know how drinking affects our brains and bodies during the night.

We’ve consulted with experts who have shared the reasons why alcohol frequently sabotages our sleep…

What happens to your body when you drink alcohol?

“When you drink alcohol, your body prioritises breaking down alcohol over other bodily processes, leading to the accumulation of toxic byproducts like acetaldehyde, which can cause inflammation and fatigue,” explains Dr Ashwin Sharma, a leading medical professional at MedExpress. “Alcohol initially depresses the central nervous system, producing feelings of relaxation or euphoria.

“However, as alcohol is metabolised, the brain compensates by becoming more excitable, leading to restlessness, disrupted sleep, and increased heart rate during the second half of the night.”

Consuming too much alcohol can also impact the part of the brain which regulates your internal clock.

“It impacts the hypothalamus, the brain region that regulates circadian rhythms, potentially interfering with your internal clock,” says Dr Steve Allder, consultant neurologist at Re:Cognition Health.

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Is the quality of sleep worse after a night of drinking?

“The quality of sleep is almost always worse after consuming alcohol,” confirms Allder. “Alcohol suppresses rapid eye movement (REM) sleep during the first half of the night. As the body metabolises the alcohol, there’s a rebound effect, leading to lighter, more fragmented sleep in the second half.

“It also disrupts the restorative properties of slow-wave sleep, leaving you less refreshed the next day.”

This can lead to frequent wake-ups, causing fragmented sleep.

“Alcohol is a diuretic, causing frequent urination and dehydration, which can lead to fragmented sleep and early morning awakenings,” explains Allder.

What are the short-term consequences of disrupted sleep after drinking?

After a night of poor-quality sleep due to alcohol, you might experience cognitive effects and mood changes.

“You’re likely to feel fatigued, sluggish, and mentally foggy due to disrupted sleep and dehydration,” says Sharma. “Alcohol can also cause headaches, dizziness, and a dry mouth due to fluid loss.

“Mood disturbances like irritability, anxiety, and even depression are also common, driven by neurotransmitter imbalances caused by alcohol’s effects on the brain.”

What happens if you drink regularly during the festive period?

“Regular drinking over the festive season can create a cycle of poor sleep and increased fatigue,” warns Sharma. “As your body struggles to maintain a natural sleep-wake rhythm, you may develop chronic sleep debt, making it harder to function during the day.

“Repeated alcohol consumption can also weaken your immune system, making you more susceptible to infections.”

Alcohol-related sleep disruptions over a prolonged can also lead to an array of serious mental and physical problems.

“Long-term alcohol-related sleep disruptions can result in persistent insomnia, chronic fatigue, and increasing the risks of mental health issues like depression and anxiety,” says Sharma. “The circadian rhythm may become misaligned, making it difficult to maintain a regular sleep schedule.

“Over time, poor sleep can contribute to cardiovascular problems, reduced cognitive function and a weakened immune response, increasing the risk of various chronic diseases.”

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How can people prevent these effects and improve their sleep?

“To mitigate alcohol’s effects on sleep, try pacing yourself by drinking water between alcoholic drinks to stay hydrated,” advises Sharma. “Also, avoid drinking alcohol within three hours of bedtime to give your body time to metabolise it.”

A consistent sleep routine and exposure to light can also help.

“Prioritise a consistent sleep routine by going to bed and waking up at the same time each day, and engage in light-exposure therapy during the daylight hours to help regulate the circadian rhythm after disrupted sleep,” recommends Sharma.