Drinking Coffee At Night May Increase Impulsivity In Women: Study

A new study has warned against consuming caffeine during night-time hours, particularly for women. Biologists from UTEP observed a noticeable increase in impulsivity linked to late-night coffee consumption.

The findings, published in the journal iScience, suggest that caffeine disrupts behavioural inhibition during night hours, leading to heightened risk-taking behaviour.

The research team explored this behaviour using Drosophila melanogaster, a type of fruit fly often used in genetic and behavioural studies due to its similarities with human biology.

They introduced caffeine into the flies’ diet and studied behavioural changes under varying conditions, altering the time of caffeine consumption, the quantity, and combining it with sleep deprivation.

The study showed a clear distinction between daytime and nighttime caffeine effects.

According to Erick Saldes, a research specialist at the University of Illinois College of Medicine Peoria, fruit flies typically stop moving when exposed to strong airflow, a naturally unpleasant sensation.

However, those given caffeine at night did not exhibit this restraint and instead displayed reckless movement, including chaotic flying.

“We found that flies consuming caffeine at night were less able to suppress movement, displaying impulsive behaviours such as reckless flying despite these aversive conditions,” Saldes explained.

In contrast, those who consumed caffeine during the day retained normal inhibitory behaviour.

Women More Affected

A key finding from the study is that female flies were more affected than males, despite having similar caffeine levels. This suggests a sex-based difference in physiological sensitivity to caffeine.

Professor Kyung-An Han from UTEP’s Department of Biological Sciences highlighted the importance of this discovery.

“Flies don’t have human hormones like oestrogen, suggesting that other genetic or physiological factors are driving the heightened sensitivity in females,” she said.

Han believes that further studies could uncover the underlying biological mechanisms responsible for these sex-specific responses.

Though the study was conducted on fruit flies, its implications may extend to humans, particularly women who work night shifts or rely on caffeine for alertness.

The researchers stress that this impulsivity could result in unsafe or poor decision-making, especially in high-stress professions such as healthcare, aviation, or defence.

The UTEP team hopes to expand their research to better understand how nighttime physiology influences caffeine’s behavioural effects and to determine whether similar patterns are observed in humans.

The study opens new avenues for gender-specific health recommendations related to caffeine consumption and sleep cycles.

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