For many people, that morning cup of coffee is an essential part of their daily routine, but have you ever wondered exactly what happens inside your body after taking that first sip? Researchers at the British Dietetic Association have the answer for you. Coffee starts kicking in just 10 minutes after the first sip. Some can be absorbed through the mouth and stomach, but most of the absorption is in the first part of the intestines. That’s when you feel the tell-tale energy boost, though it’s kind of misleading. That’s because caffeine doesn’t actually provide energy. Instead, it works by blocking your body from interacting with adenosine, a chemical lurking inside you that makes you feel tired. Introducing caffeine into the body is like sticking a key in a lock that turns off the adenosine receptors and prevents us from feeling tired, in turn making us feel more awake. After 20 minutes, there’s a spike in blood pressure as the caffeine causes your blood vessels to constrict, increasing your heart rate. The effects of caffeine on the body peaks at 45 minutes. Once you hit the 60-minute mark, the blood will start to have a diuretic effect. Coffee doesn’t just make you need to urinate more, it also stimulates your bowels, activating contractions in your colon and internal muscles. Approximately 90 minutes after your morning coffee, the stimulating effects begin to fade, as well as the diuretic effects. That’s when you might experience feelings of fatigue, anxiety and poor concentration. For most people, the amount of caffeine falls by around half after about 6 hours, with all of the caffeine leaving your system completely after 12 hours. That’s why sleep experts recommend avoiding caffeine at least 8 hours before bedtime. So, think twice before reaching for that afternoon brew that you think will be a welcome pick-me-up.
