We all know that a late cup of coffee can mess up our sleep, and most of us, including me, thought it is because the caffeine in the coffee is a stimulant, keeping us awake.
In small amounts caffeine is a stimulant, increasing alertness and decreasing fatigue but that is not the reason why we can not sleep. Research has shown that the late dose of caffeine delays your internal clock by some 40 mins.
The circadian clock, our inner clock, regulates our daily metabolic rhythm, coordinating our biology with the day-night cycle. Caffeine directly affects our adenosine receptors, increasing the level of cyclic AMP, a decisive actor in our circadian clock, resulting in a delayed peak of melatonin (our sleep hormone) in our system.
The research shows that the late cup of coffee can disturb your sleep rhythm but it could path the way for new methods of reducing jet lag. For those non coffee drinkers who still have problems falling asleep at night, soft drinks and tea have caffeine too, some more than coffee.