caffeine
1 of 1nouna substance present in coffee or tea that makes one's brain more active
Learn more on WikipediaCaffeine is a natural stimulant found in various beverages and foods, such as coffee, tea, energy drinks, and chocolate. It works by blocking the action of adenosine, a neurotransmitter that promotes relaxation and sleepiness. By doing so, caffeine increases alertness and reduces fatigue. Caffeine also stimulates the release of adrenaline, which can temporarily increase heart rate and blood pressure. Moderate consumption of caffeine is generally considered safe for most people and may even have some health benefits, such as improved mental alertness and enhanced exercise performance. However, excessive intake can lead to side effects like jitteriness, insomnia, headaches, and increased heart rate.
- The caffeine in her morning coffee helped her focus at work.
- He avoided caffeine after 3 PM to sleep better at night.
- Green tea has less caffeine than espresso but still gives energy.
- Too much caffeine can make you feel jittery or anxious.
- Decaf coffee has most of the caffeine removed.