There are a few potential reasons why some people may feel sleepy after consuming caffeine:
- Caffeine tolerance: Regular caffeine consumption can lead to increased tolerance over time. As a result, the stimulating effects may diminish, and the person may feel tired or sleepy after drinking coffee or other caffeinated beverages.
- Adenosine rebound: Caffeine works by blocking adenosine receptors in the brain. Adenosine is a neurotransmitter that promotes sleep. When caffeine wears off, the built-up adenosine can bind to its receptors, causing a sudden onset of sleepiness.
- Sugar crash: Many caffeinated drinks, such as energy drinks or sweetened coffee beverages, contain high amounts of sugar. The initial sugar rush can provide a temporary energy boost, but when blood sugar levels drop (known as a sugar crash), it can lead to feelings of tiredness and fatigue.
