Coffee contains caffeine, which helps to refresh and invigorate, but long-term or excessive consumption can inhibit adenosine receptors, leading to chronic sleep deprivation.
Professor Richard Alan Friedman, director of the Payne Whitney Psychiatric Clinic, recounts a case of a 32-year-old patient who dozed off while waiting at a red light and was detained by the police on suspicion of using alcohol or drugs while driving. In reality, the man’s sudden sleepiness was due to chronic sleep deprivation. Work pressure forced him to try to sleep only 5 hours a day instead of the recommended 7-9 hours. To keep himself alert, focused, and energized, he consumed 6 cups of coffee daily.
A cup of coffee (236 ml) provides about 100 mg of caffeine. Consuming 400-500 mg of caffeine per day is considered safe, while levels above 1,200 mg can lead to toxicity, with symptoms such as seizures or arrhythmias. Like the aforementioned patient, he was unaware that his brain was suffering from severe sleep deprivation. The temporary feeling of alertness was merely a trick played by caffeine. In reality, no medication, including caffeine, can effectively reverse the state of sleep deprivation.
There is a substance in the brain called adenosine that plays a crucial role in regulating sleep. Adenosine levels are lowest in the morning when we just wake up and gradually increase throughout the day, creating the pressure for the body to need sleep at night. Adenosine is cleared from the brain during sleep, helping us feel alert upon waking. Caffeine is a strong antagonist of adenosine receptors, blocking its sedative effects and making you feel excited and awake.
The problem arises when you cut short your sleep; adenosine is not completely cleared from the brain. The more sleep-deprived you are, the higher the concentration of residual adenosine in the brain, which creates a persistent feeling of fatigue and drowsiness, impairing cognitive function.
The brain attempts to address this situation by increasing the number of adenosine receptors, making you feel tired and in need of sleep. However, instead of sleeping, you drink more coffee, unaware that only getting enough sleep can prevent the rise of adenosine.
Lack of sleep not only makes you tired but also weakens the brain’s ability to consolidate memories. Sleep deprivation can also lead to irritability and a lack of emotional control in healthy individuals, exacerbating depression and anxiety disorders in those with mental health issues.
Caffeine in black coffee helps keep you awake. (Photo: Freepik).
How to Ensure Coffee Does Not Affect Sleep
According to research from the U.S. Food and Drug Administration (FDA), the half-life (the time it takes for the body to metabolize 50% of the consumed caffeine) typically ranges from 4 to 6 hours. An adult should not consume more than 4-5 cups of coffee a day. For those sensitive to caffeine, this number may need to be lower, and consulting a physician is advisable if necessary.
Moreover, drinking coffee throughout the day can make it difficult to sleep, even counteracting sedative medications. The best approach is to drink coffee in the morning and avoid it after lunch. Some individuals who metabolize caffeine slowly due to genetics may experience insomnia even after drinking coffee early in the morning; thus, they should switch to tea.
One undeniable fact is that you cannot rely on caffeine to combat sleepiness throughout your life due to the increasing residual adenosine levels in the brain, which will eventually lead you to “crash.”
“When that happens, do not panic and rush to take sleeping pills; allow your brain to rest naturally,” advises Professor Friedman.
