Caffeine Chaos: Fruit Flies Become Reckless After Late-Night Coffee Binge

According to a study published in the journal iScience on August 7, 2025, fruit flies exhibited impulsive and reckless behavior after consuming caffeine at night. Researchers at the University of Texas at El Paso discovered that the flies were less able to suppress movement and displayed "reckless flying" when exposed to strong winds, a behavior not seen in flies that did not consume caffeine.

The study's lead author, Dr. Paul Sabandal, explained that the impact of caffeine was more pronounced in female fruit flies compared to males, despite the flies having the same levels of the stimulant. This suggests there may be genetic or physiological factors at play, as the flies do not have human hormones.

Another intriguing finding was that the reckless behavior was only observed in flies that consumed caffeine at night, and not during the day. The researchers say uncovering the mechanisms behind this could help better understand how nighttime physiology and sex-specific factors influence caffeine's effects.

The study's implications could be significant, as caffeine is the most widely consumed psychoactive substance in the world, with about 85% of adults in the U.S. using it regularly. The researchers warn the findings could have negative consequences for women and people who work night shifts, as previous research has linked caffeine consumption to impulsive shopping habits.