The coffee sleep cycle Caffeine’s effects on adenosine receptors, a build-up of caffeine tolerance, and changes in blood sugars all contribute to why coffee makes us sleepy.

Guarana is high in caffeine and is derived from the seeds of a South American tree. Learn about the health benefits, dosage, and side effects of this supplement.

Caffeine's stimulating effects can paradoxically lead to sleepiness due to tolerance, adenosine receptor changes, and individual metabolic differences.

An average cup of coffee contains 95 mg of caffeine, but some types contain over 500 mg. This article lists the caffeine content in different coffee types.

How is decaf coffee made? There are four main ways manufacturers remove the caffeine from coffee, according to the National Coffee Association. The European method is most common, which uses a ...

Are you drinking too much coffee? A gastroenterologist and a caffeine researcher share surprising insights about the psychoactive drug.

Since caffeine works by “blocking sleep-promoting receptors in your brain called adenosine receptors,” Lee said that people who drink coffee too late in the day may struggle to sleep at night.

Caffeine is a popular stimulant. However, some people may experience caffeine sensitivity, which can cause nausea, anxiety, and trembling after consuming low amounts of caffeine.

The best pre-workouts can boost energy, endurance and recovery to help you make the most of every workout. Here are the blends we recommend, based on expert insights.

But other people may have less of a caffeine tolerance, or may be advised by a doctor to limit caffeine consumption — such as those who are pregnant, breastfeeding or taking certain medications ...

Caffeine occurs naturally in plants and is found in many foods and drinks, such as coffee, chocolate, and cola. Although too much caffeine can cause unpleasant side effects, accidental overdose is ...