Your daily dose of caffeine is a hot topic in scientific debates and research. According to the official recommendations from the U.S. Food and Drug Administration (FDA), this dose should not exceed 400 milligrams per day, which is roughly equivalent to four cups of coffee.
Recently, an international team of experts released findings from a new study suggesting that the daily limit could be significantly lower. However, that lower amount is still enough to fully wake you up and keep you energized for an extended period without causing adverse effects.
What Scientists Are Saying
Researchers indicate that many people consume caffeine to stay active throughout the day. However, excessive amounts can lead to anxiety and insomnia.
So, how can you optimize your caffeine intake to reap its maximum benefits without jeopardizing your health?
It turns out that consuming between 100 to 150 milligrams of caffeine—equivalent to 1 to 1.5 cups of coffee—is enough to maintain alertness. “This is the dose that provides a healthy boost of energy,” said Astrid Nelig, honorary director of research at the French National Institute for Health Protection.
According to her, we start feeling more alert just five minutes after drinking coffee. The effect intensifies and peaks around 15 minutes later. Depending on what you’ve eaten and your metabolic rate, this timing can vary, potentially stretching up to two hours.
A Spoonful of Tar in Your Coffee
Despite the benefits of caffeine, scientists emphasize that large quantities can lead to negative consequences. Primarily, they disrupt sleep, which in turn can lead to numerous health issues.
The impact of caffeine on sleep depends on how quickly a person metabolizes caffeine, explained Gregory Marcus, a professor of medicine at the University of California, San Francisco. He added that after drinking coffee, people with a slow metabolism sleep nearly an hour less than usual, while those with a fast metabolism typically experience no change in their sleep patterns, as reported by the Daily Mail.
When to Drink Your First Cup of the Day?
The authors of the new study recommend waiting until at least 9:30 AM for your first cup of coffee. This timing not only maximizes the drink’s effects but also makes it safer.
Cortisol levels (the stress hormone) are highest upon waking. Drinking coffee too early can raise cortisol even more and trigger unnecessary anxiety.
One previous study showed that cortisol levels drop throughout the day, with two significant declines occurring around 9:30 AM and 1:00 PM.
Combining already elevated cortisol with coffee can trigger a stress response. Sports dietitian Amanda Moser said this reaction can be reduced by delaying your first cup by at least an hour.
When to Drink Your Last Cup of the Day?
Experts assert that the latest time for your last cup of coffee should be six hours before bedtime. So, if you plan to go to sleep at 10:00 PM, your final sip of coffee should be at 4:00 PM.
However, some research teams disagree with this view. They recommend stopping coffee consumption even earlier—eight hours before sleep—to ensure a solid night’s rest. For instance, Dr. Deirdre Conroy, a sleep specialist at the University of Michigan, believes that individuals have vastly different sensitivities to caffeine. Those who consume it more frequently may react differently than those who typically avoid it.
