Drinking coffee in the late afternoon: Why do some people have trouble sleeping while others don't?

Genetic differences determine sensitivity to caffeine.

According to studies published in the U.S. National Library of Medicine, genetic variations related to the adenosine receptor (a sleep-inducing substance) may affect how the body responds to caffeine. People who are less sensitive may experience insomnia more easily.

Professor Hans-Peter Landolt, a sleep research expert at the University of Zurich (Switzerland), said that genetic differences may explain why some people can drink coffee late at night and still sleep normally, while others experience insomnia even with only a small amount.

Caffeine metabolism rates vary.

Not everyone processes caffeine the same way. According to the National Sleep Foundation, some people metabolize caffeine more quickly, allowing it to be eliminated from the body sooner and reducing its impact on sleep.

The body becomes accustomed to caffeine over time.

Regular coffee drinkers may develop tolerance, causing the stimulating effects to gradually diminish. According to international neuroscience studies, long-term caffeine use can alter the brain's response, making the feeling of alertness less intense than before.

Dr. Michael Breus, a member of the American Academy of Sleep Medicine, states: "The body may adapt to caffeine, but that doesn't mean it no longer affects sleep."

Being able to sleep doesn't necessarily mean having quality sleep.

While some people may still be able to fall asleep after drinking coffee late at night, caffeine can still impair the quality of deep sleep. According to the National Sleep Foundation, caffeine can lead to lighter sleep without users realizing it.

Whether you can drink coffee in the late afternoon and still sleep well is mainly due to genetics, metabolic rate, and caffeine consumption habits . However, experts still recommend limiting coffee at the end of the day to protect sleep and long-term health.