Caffeine is the most widely consumed stimulant in the world. We drink it in our coffee, we consume it in our cans of Coke and Pepsi. People take in so much of this drug, they rarely think twice about it.

Caffeine is found naturally in so many of our foods and beverages, we take it for granted. On top of that, it’s often referenced for its positive effects on attention and mental alertness.

Not only is caffeine found abundantly available in natural and supplemented foods and beverages, you’ll also find it in products sold over the counter for fatigue, migraines and colds.

But what are caffeine’s effects on our thinking? Is it helping or hindering our thought processes? Let’s find out…

Blood levels of caffeine peak in as few as 15 minutes and on average 45 minutes after ingestion. Some studies suggest that over 80 percent of U.S. adults and children ingest caffeine on a daily basis (Brunye et al., 2010).

Many studies indicate that the primary role caffeine has affecting our behavior is its effect on blocking the inhibitory properties of endogenous adenosine. So what? you say. Well, that inhibition results in increased dopamine, norepinephrine and glutamate. Caffeine ingestion leads to increased stimulation of your heart (cardio) and even anti-asthmatic actions.

Many studies have demonstrated that caffeine leads to enhanced cognitive performance involving various tasks (Brunye et al., 2010). It is often cited for its positive effects on vigilance, mental alertness, feeling of well-being and arousal. Caffeine also has a positive effect on various domains of attention (Trayambak et al., 2009).

Many studies show caffeine reduces response times and error rates in simple reaction time tasks, choice reaction time, and visual vigilance. Your brain appears to love caffeine too. Brain processes that have also been shown to benefit from caffeine include visual selective attention, task switching, conflict monitoring and response inhibition.

Different types of tasks are used when measuring caffeine’s effect on different types of attention. Sustained attention — e.g., attention over a prolonged time period — has been most studied. A large body of data shows caffeine positively influences sustained attention. Sustained attention often is measured by using a continuous performance task. For example, participants view a stream of stimuli (often letters) and are required to respond whenever a predetermined target is presented. Task length varies considerably.

Research also shows caffeine has positive effects on selective attention — the process of attending to meaningful sources while ignoring irrelevant ones. The research findings are indecisive; some research has failed to find a positive relationship between caffeine ingestion and selective attention.

Selective attention most often is measured by four main tasks. The visual search task is least often used to measure caffeine’s effects on selective attention.

A visual search task consists of participants identifying a predetermined target stimulus while ignoring a number of distractors. For example, a conjunction search requires participants to identify a target by at least two different attributes (e.g., find a blue capital A). These types of tasks are useful because in daily life, often it is necessary to identify objects by several attributes.

Moderate doses of caffeine — 200-300 mg — often are used in research, although doses over 500 mgs sometimes are used. The general finding is that more than moderate use does not offer additional benefits, and higher doses sometimes lead to negative effects.

So go ahead and have that cup of coffee or can of Coke. It’s likely to help your thinking… as long as you don’t overdo it.