Nighttime Caffeine Linked to Risky Behavior, Study Warns

Drinking coffee at night might do more than keep you awake. A new study suggests it could also weaken self-control and increase impulsive, risk-taking behavior.

A new study from researchers at the University of Texas has revealed a surprising side effect of consuming caffeine at night: it may significantly increase impulsive behavior and reduce the ability to control actions.

Published in the peer-reviewed journal iScience, the research examined how caffeine consumption at different times of the day affects inhibition and decision-making.

Experiments on Fruit Flies Reveal Key Insights

To better understand the behavioral effects of caffeine, scientists conducted experiments on fruit flies, whose genetic and neurological structures share important similarities with humans.

The flies were given caffeine at different times and doses. Researchers then exposed them to unpleasant conditions, such as strong air currents, to measure how well they could suppress their reactions.

Night Consumption Weakens Self-Control

The results were striking.

Fruit flies that consumed caffeine during the day showed no significant behavioral changes. However, those given caffeine at night displayed clear signs of impulsivity. Despite adverse conditions, they failed to control their movements and exhibited what researchers described as “reckless flying.”

Stronger Effects Observed in Females

Another notable finding was the difference between male and female subjects.

Although both had similar levels of caffeine in their systems, female fruit flies showed significantly higher impulsive behavior. Researchers believe this may be linked to genetic or physiological differences, as fruit flies do not have hormones like estrogen found in humans.

What It Could Mean for Humans

Caffeine is the most widely consumed psychoactive substance in the world. These findings raise important questions about how nighttime consumption might affect human behavior—especially for shift workers, healthcare professionals, and military personnel who rely on caffeine to stay alert at night.

Experts say further research is needed, but the study suggests that when you drink your coffee may be just as important as how much you consume.

Caffeine is the world’s most widely consumed psychoactive substance, making these findings especially relevant for millions of people worldwide.