Do you often drink coffee at night to stay awake? A recent study from The University of Texas at El Paso advises caution. Researchers have found that consuming caffeine late in the day can boost impulsive behavior and potentially lead to careless actions.
The research, published in iScience, explored how nighttime caffeine affects self-control and impulsivity in fruit flies. The study was guided by Erick Saldes, Ph.D., Paul Sabandal, Ph.D., and Kyung-An Han, Ph.D.
iScienceThe researchers used Drosophila melanogaster, common fruit flies, due to their genetic and neurological similarities with humans. According to Han, these qualities make them excellent subjects for studying complex behaviors.
"Caffeine is the most commonly used psychoactive substance globally," noted Sabandal, a research assistant professor at UTEP's Department of Biological Sciences. "Considering its widespread use, we wanted to see if other factors could influence caffeine’s impact on behavior."
The team carried out experiments by introducing different amounts of caffeine into the flies' diets during various conditions—including different times and with sleep deprivation. They then tested impulsivity by measuring the flies' ability to stop moving when exposed to strong air currents, an uncomfortable sensation.
"Under typical circumstances, fruit flies stop moving when faced with strong airflow," explained Saldes, now at the University of Illinois College of Medicine Peoria but formerly a doctoral student at UTEP. "However, flies consuming caffeine at night were less able to control their movement, showing impulsive and risky behaviors despite these conditions."
Interestingly, daytime consumption did not result in similar reckless behavior.
The study also found sex-based differences: female flies exhibited greater caffeine-related impulses than males, even with comparable caffeine levels.
"Since fruit flies lack human hormones like estrogen, other genetic or physiological factors must be enhancing females' sensitivity," said Kyung-An Han, Professor of Biological Sciences. "Understanding these mechanisms will help us better grasp how nighttime influences and sex-specific elements affect the impact of caffeine."
The research could have negative implications for shift workers, healthcare professionals, and military personnel who drink coffee at night, especially females.
This study was conducted in Professor Han’s lab within UTEP's Department of Biological Sciences. The lab focuses on understanding behavioral flexibility, learning, memory, addiction, gene-by-environment interactions, Alzheimer’s disease, and related conditions.