Why does coffee sometimes make you tired?

The major active element in coffee, caffeine, has a well-deserved reputation as an energy booster. Caffeine, on the other hand, is a medication, which means it affects each of us differently based on our intake patterns and genetics.

“The paradox of caffeine is that it improves concentration and alertness in the short term. It helps with some cognitive tasks and energy levels,” said Mark Stein, a professor in the University of Washington’s Department of Psychiatry and Behavioral Sciences who has researched the effects of coffee on people with attention deficit hyperactivity disorder. “However, the cumulative effect — or long-term influence — is the inverse.”

Caffeine’s paradoxical effects are due to its influence on what experts call “sleep pressure,” which fuels how drowsy we grow as the day progresses. Our bodies have a biological clock that tells us to go back to sleep later in the day from the moment we wake up.

Seth Blackshaw, a sleep researcher at Johns Hopkins University, said that while researchers are still discovering how sleep pressure builds up in the body, our cells and tissues utilise and burn energy in the form of adenosine triphosphate, or ATP, throughout the day. Our cells produce a molecule called adenosine as a byproduct as that ATP is used up – while we think, exercise, do errands, or wait on conference calls. The adenosine then binds to receptors in the brain, causing us to fall asleep faster.

Caffeine chemically resembles adenosine enough on the molecular level to occupy those binding sites, preventing adenosine from attaching to those receptors. As a result, coffee helps us feel more awake by momentarily suppressing sleep pressure. Meanwhile, adenosine levels in the body continue to rise.

“Once the coffee wears off, you have to pay it back with a really high amount of sleep pressure,” Blackshaw explained. In reality, sleep is the only way to relieve and reset a high degree of sleep pressure.

Read more • seattletimes.com

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