Cutting out coffee for just a fortnight could lead to reduced impulsivity and stress levels, while opting for decaf might enhance sleep quality and memory, according to a recent study.

In this research, scientists monitored 62 healthy adults to explore the impact of coffee on both the body and the brain. The participants were split into two groups: 31 individuals who consumed coffee regularly and 31 who did not.

At the beginning of the study, all participants provided samples of blood, urine, and stool.

They also filled out questionnaires regarding their mood and behavior and underwent tests to assess memory and cognitive abilities.

The regular coffee consumers were instructed to completely abstain from coffee for two weeks. Following this period, they were randomly assigned to drink either caffeinated or decaf coffee for the next 21 days. Of these, 16 participants received caffeinated coffee, while 15 switched to decaf.

Researchers then evaluated the changes in participants during both the withdrawal phase and after coffee was reintroduced.

They found regular coffee drinkers experienced more impulsive behaviour and emotional reactivity than people who did not drink coffee.

But after coffee drinkers gave up their habit for a fortnight, both measures fell.

Quitting coffee for just two weeks may make people less impulsive and less stressed, while switching to decaf could improve sleep and memory, a study suggests 

When coffee was re-introduced, the effects differed depending on the type consumed.

Participants given caffeinated coffee reported lower anxiety and psychological distress.

Those assigned decaf saw improvements in sleep quality, physical activity and memory scores.

Researchers said the findings suggest coffee may affect the body in ways that go well beyond the caffeine hit many drinkers rely on each morning.

The study, published this week in Nature Communications, was led by researchers at University College Cork in Ireland.

Alongside the behavioural findings, scientists also discovered that regular coffee drinkers had a distinctly different gut microbiome from non-drinkers.

The gut microbiome refers to the trillions of bacteria and other microbes living in the digestive system. Scientists increasingly believe it may help shape digestion, immunity, metabolism, mood and even brain health.

Some of the bacterial patterns seen in coffee drinkers began to shift back towards levels seen in non-drinkers after the two-week withdrawal period.

When coffee was re-introduced, both caffeinated and decaffeinated versions triggered fresh bacterial changes.

The team said this suggests some of coffee’s effects may come from naturally occurring plant compounds rather than caffeine alone.

These substances, known as phenolic acids, are antioxidants also found in fruit, vegetables and other plant foods.

Researchers also found signs coffee could influence inflammation.

At the start of the trial, regular coffee drinkers had lower levels of C-reactive protein, a common marker linked to inflammation in the body.

They also had higher levels of IL-10, an anti-inflammatory molecule.

When coffee was withdrawn, some inflammatory markers rose.

After coffee was reintroduced, both the caffeinated and decaf groups showed a reduced inflammatory response in laboratory testing.

However, the researchers stressed the study does not prove coffee directly causes better health, improved memory or changes in personality.

The trial was relatively small, involving only 62 people.

Some of the gains seen in memory tests may simply have reflected participants becoming more familiar with repeating the same tasks.

The authors also said the sample lacked sufficient diversity and may not have been large enough to detect more subtle effects.

Previous studies have linked moderate coffee intake to lower risks of type 2 diabetes, liver disease and some heart conditions.

But coffee can also worsen anxiety, palpitations and poor sleep in sensitive people, particularly when consumed in large amounts or late in the day.

The researchers said larger studies are now needed to confirm whether the microbial changes seen in coffee drinkers translate into meaningful long-term health benefits.