What Is caffeine and why does it wake me up in the morning?

Just the smell of freshly brewed coffee drifting through the air can be enough to awaken your senses. But just what is caffeine, and how does it work?

Caffeine belongs to a class of drugs called stimulants, which increase activity in the nervous system. Consumed mainly in beverages like coffee, tea, energy drinks, and some carbonated drinks, caffeine is the most widely used stimulant in the world.

Caffeine helps us wake up by increasing cortisol, a hormone, and by blocking a sleep-inducing chemical called adenosine. Normally, adenosine builds up in your brain throughout the day, which is why you feel sleepy at night. Caffeine attaches to adenosine receptors, interrupting this process. The result is that you feel more alert.

Most people feel the energizing effects of caffeine between 30 to 60 minutes after ingesting it. When used in moderation, caffeine is safe. The recommended daily maximum for adults is 400mg, with lower limits for children and teens, pregnant women, and women who are breastfeeding. For reference, an eight-ounce cup of brewed coffee has 100 to 200mg of caffeine.