Nighttime Coffee Consumption Linked to Impulsivity in Women

New research indicates that drinking coffee at night may lead to increased impulsive behavior, particularly among women. A team of biologists from The University of Texas at El Paso (UTEP) conducted the study, which suggests that nighttime caffeine consumption can trigger reckless actions. This finding poses potential risks for specific groups, including shift workers and military personnel, who often rely on caffeine to stay alert during late hours.

The study, published in the journal iScience, utilized the fruit fly species Drosophila melanogaster to investigate how nighttime caffeine intake affects impulsivity and inhibition. Fruit flies serve as an effective model for studying complex behaviors due to their genetic and neural similarities to humans.

Researchers designed a series of experiments to assess the impact of caffeine on the flies under various conditions, including different doses and the timing of consumption—comparing nighttime intake to daytime consumption while also factoring in sleep deprivation. The level of impulsivity was measured by observing the flies’ ability to suppress movement in response to a strong airflow, a naturally unpleasant stimulus.

According to Erick Saldes, a science research specialist at the University of Illinois College of Medicine Peoria, “Under normal circumstances, flies stop moving when exposed to strong airflow. We found that flies consuming caffeine at night were less able to suppress movement, displaying impulsive behaviors such as reckless flying despite these aversive conditions.”

Interestingly, flies that consumed caffeine during the daytime did not exhibit the same reckless flying behavior. The researchers also noted a significant difference in impulsivity between male and female flies. Despite having comparable levels of caffeine in their systems, females displayed greater impulsivity than males.

Biological Sciences Professor Kyung-An Han stated, “Flies don’t have human hormones like estrogen, suggesting that other genetic or physiological factors are driving the heightened sensitivity in females.” Understanding these mechanisms could provide insight into how nighttime physiology and sex-specific factors influence the effects of caffeine.

The implications of this study reach beyond the laboratory. For individuals who consume caffeine at night, especially women, awareness of its potential effects on behavior may be crucial. As caffeine remains a popular stimulant worldwide, further research could illuminate its impact on different populations and settings.

These findings highlight the importance of considering how timing and biological differences can affect caffeine’s influence on behavior. As more studies emerge, they may shape guidelines for caffeine consumption, particularly in high-stakes environments where impulsivity can have serious consequences.