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A recent study indicates that caffeine consumed after dark may increase impulsivity, indicating potential concerns for night-shift workers, students, and individuals in high-responsibility roles.
TheDigger Intelligence Unit
That Late Cup Could Carry Hidden Risks
For many, nighttime coffee is essential—nurses on long shifts, students cramming for exams, drivers fighting fatigue.
Research indicates that late-night caffeine may influence wakefulness, impulsivity, and self-control. Scientists note that women might be particularly affected.
The Science Behind the Sip
Researchers at the University of Texas at El Paso, in a study published in iScience, observed that fruit flies administered caffeine at night ignored signals that usually deterred them, moving into areas with unfavourable airflow.
Daytime caffeine didn’t trigger the same response, suggesting timing is a critical factor.
Female flies reacted more strongly than males, although caffeine levels were similar. “Flies lack human hormones like estrogen, so other genetic or physiological factors must drive this sensitivity,” noted Professor Kyung-An Han. The finding raises questions about whether women may be more prone to the effects of nighttime caffeine.
From Lab to Life
These findings may be relevant beyond laboratory settings. For instance, a nurse working the night shift may rely on caffeine for alertness, but increased impulsivity could potentially affect performance. A student studying late may experience distraction and find it challenging to avoid risky decisions online or in social settings. For drivers, impulsivity can increase driving risks.
Tips for Smarter Caffeine Use
Health experts note that caffeine is not just about quantity, but also about timing.
Reducing coffee intake at least six hours before bedtime can help minimise its influence on sleep and self-control. Individuals, especially women, may benefit from monitoring how late-night caffeine consumption affects mood and focus.
For those working overnight, alternatives such as short naps, hydration, or light physical activity can support alertness without excessively stimulating the brain. Consuming caffeine in moderation is recommended.
Up to 400 milligrams of caffeine is considered safe for most adults, but timing and individual sensitivity matter.
A Familiar Dilemma
For example, Blessing, a medical student in Lagos, reports using coffee to remain awake during late-night study sessions. She notes, “It keeps me awake, but sometimes I feel jittery and end up scrolling on my phone instead of reading.”
Her experience mirrors the study’s findings: alertness paired with impulsivity.
Or consider Fatima, a nurse in Abuja, who says she’s cut back on coffee during night shifts. “I realised I was more irritable and less focused when I drank it after midnight. Now I stick to water and short breaks.”
A New Dimension
With 85% of U.S. adults consuming caffeine regularly — and similar patterns worldwide — this study adds a new dimension: not just how much we drink, but when we drink it may shape our behaviour.
For women, especially, that late-night coffee could actually reduce self-control, potentially affecting their performance at work, in class, and in daily tasks.
