Drinking Coffee at Night May Increase Impulsive Behaviour, Study Finds

Does your evening coffee do more than keep you awake? A new study reveals that caffeine at night can increase impulsive behaviour and risk-taking, especially in women.

Drinking coffee in the evening to stay awake could have surprising effects on behaviour, according to new research from the University of Texas at El Paso. Scientists discovered that consuming caffeine during the night may lead to more impulsive behaviour, making people more likely to take risks or lose control.

The study, published in iScience, investigated how caffeine influences behaviour based on the time of day. To do this, they used fruit flies, specifically Drosophila melanogaster, which are often studied because their brain functions and genetics are similar to those of humans.

Behaviour Changes

Researchers examined how caffeine affected the flies’ ability to regulate their actions. They exposed the flies to varying levels of caffeine, both during the day and at night, and also looked at the impact of sleep deprivation.

Usually, fruit flies stop moving when exposed to strong airflow, as they find it unpleasant. However, flies that received caffeine at night were less likely to stop moving, continuing to act in a reckless manner.

This indicated a decrease in self-control and an increase in impulsive behaviour. In contrast, flies that consumed caffeine during the day behaved normally.

Gender Difference

The study also revealed significant differences between male and female flies. Although both had similar levels of caffeine in their systems, females displayed stronger impulsive responses. According to Professor Han, this cannot be explained by human hormones like estrogen, suggesting other biological factors are at play.

Wider Impact

These findings may have practical relevance, especially for people who consume caffeine at night, such as shift workers, healthcare professionals, and military personnel. The researchers suggest that women may be particularly affected.

The work was conducted in Han’s lab, which focuses on how the brain controls behaviour, including learning, memory, and addiction, as well as how genes and the environment interact in conditions like Alzheimer’s disease.