Drinking Coffee at Night May Make You More Reckless… A Study Reveals an Unexpected Effect
Dubai, August 6, 2025 – (Qahwa World) – Coffee may be a late-night ally for millions worldwide, but new research suggests it could come at a cost to our behavioral control—especially when consumed at night.
A groundbreaking study from the University of Texas at El Paso (UTEP), published in iScience, reveals that nighttime caffeine intake increases impulsivity in fruit flies (Drosophila melanogaster), disrupting their natural ability to suppress risky behavior. Though the findings are drawn from insects, the implications ripple across the broader conversation about how we, as humans, consume coffee—particularly in professions where mental control is crucial.
A Window Into the Brain—Through the Wings of a Fly
The UTEP team, led by neuroscientists Dr. Erick Saldes, Dr. Paul Sabandal, and Dr. Kyung-An Han, turned to fruit flies for answers—not out of simplicity, but precision. Despite their size, Drosophila shares striking genetic and neurological parallels with humans. And when it comes to studying behavioral control, they offer a surprisingly accurate model.
Their experiments involved introducing caffeine into the diets of the flies under controlled conditions. The results were clear: flies consuming caffeine at night became more impulsive, failing to suppress movement even when exposed to a strong, aversive airflow stimulus—something they would normally avoid. In simple terms, they began “flying recklessly,” ignoring their natural instinct to stop.
Daytime caffeine, by contrast, had no such effect.
The Caffeine Curve: Timing Matters
“We often think of caffeine as a straightforward stimulant,” said Dr. Sabandal in a UTEP release. “But timing is everything. At night, it seems to interfere with deeper behavioral mechanisms, including those related to self-restraint.”
The researchers also observed a pronounced sex-based difference. Female flies exhibited a stronger impulsive response than males, despite having similar caffeine levels in their system. This finding opens the door to deeper questions about physiological sensitivity and whether women might be more susceptible to certain caffeine-related effects—though more research in humans is needed.
The Dopamine Connection
The impulsivity wasn’t just a behavioral quirk—it had a neurological fingerprint. The researchers found that caffeine’s effects were tightly linked to dopamine signaling, a key pathway in the brain associated with motivation, reward, and control. Mutant flies that couldn’t synthesize or release dopamine did not show impulsive behavior, even after caffeine consumption.
Additionally, a specific cluster of neurons—known as the PAM cluster—was identified as the control center for this caffeine-triggered wakefulness and impulsivity. In a fascinating twist, when these neurons were artificially activated, the flies lost sleep even without caffeine.
Implications for Human Coffee Habits
Although fruit flies are not humans, the study raises provocative questions. What happens when shift workers, nurses, pilots, or security officers regularly consume coffee during the night? Could there be subtle effects on decision-making, judgment, or reaction to stress?
“The findings highlight a possible trade-off between staying awake and staying in control,” noted Dr. Han, emphasizing the need for further research in mammals.
For coffee lovers—especially those who sip through long nights—this study is a reminder that caffeine is not just about alertness. It interacts deeply with our neurobiology, and its effects may vary depending on when and how we consume it.
Final Sip
At Qahwa World, we’ve long championed coffee as a cultural, sensory, and even scientific marvel. But science also reminds us that every sip tells a more complex story. This research from UTEP adds a fascinating chapter—one that invites us to rethink not just how much coffee we drink, but when we drink it.
After all, even the perfect cup may have its hour.
Key Takeaways:
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Nighttime caffeine increases impulsivity in fruit flies.
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The effect is tied to dopamine circuits and specific brain regions.
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Females are more sensitive than males.
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Implications extend to humans, especially shift workers.
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Timing—not just quantity—matters when it comes to coffee
