Caffeine is a stimulant that increases alertness and boosts energy levels. Caffeine itself doesn’t cause drowsiness. Coffee, however, is a complex beverage, and drinking it can make you feel tired at times. Here’s a look at why coffee can actually make you sleepy and fatigued, even though it’s caffeinated.
Adenosine Will Make You Sleepy When the Caffeine Wears Off
The caffeine in coffee blocks adenosine receptors in your brain from receiving adenosine, which is a neurotransmitter that causes fatigue. Although caffeine prevents your brain from receiving adenosine, it doesn’t stop your body from producing the neurotransmitter. Thus, when the caffeine wears off, there is a buildup of adenosine that will make you sleepy.
Caffeine isn’t making you sleepy, because it doesn’t impact how much adenosine your body manufacturers. It does, however, delay the effects of that adenosine so that you feel it all at once in a rush when the caffeine wears off.