How does caffeine effect your sleep?

It keeps us awake: Caffeine is a chemical found in coffee. Normally as the day progresses, we tend to feel sleepier in part due to a chemical build up of adenosine, a natural by product of our active brain. Caffeine competes with Adenosine and binds to similar brain regions as adenosine, making us feel less sleepy. Caffeine can fragment sleep if too much is taken too close to bedtime.

prevent it: Caffeine blocks a receptor in brain that modulates sleepiness.