SummaryĬaffeine’s main effect is on the brain. Because it affects your brain, caffeine is often referred to as a psychoactive drug.Īdditionally, caffeine tends to exert its effects quickly.įor instance, the amount found in one cup of coffee can take as little as 20 minutes to reach the bloodstream and about 1 hour to reach full effectiveness ( 1). This combination further stimulates the brain and promotes a state of arousal, alertness, and focus. It may also increase blood adrenaline levels and increase brain activity of the neurotransmitters dopamine and norepinephrine ( 3). This blocks the effects of adenosine, leading to reduced tiredness ( 3). Normally, adenosine levels build up over the day, making you increasingly more tired and causing you to want to go to sleep.Ĭaffeine helps you stay awake by connecting to adenosine receptors in the brain without activating them. It functions by blocking the effects of adenosine, which is a neurotransmitter that relaxes the brain and makes you feel tired ( 2). That said, caffeine’s main effect is on the brain. Once consumed, caffeine is quickly absorbed from the gut into the bloodstream.įrom there, it travels to the liver and is broken down into compounds that can affect the function of various organs.
