AUTHOR

Philip Ghezelbash

Science and Nutrition Writer

Many people start their day with a cup of coffee. Caffeine, the stimulant in coffee, is the most commonly consumed psychoactive substance in the modern world. The majority of people drink coffee, as well as other caffeinated beverages such as tea and energy drinks, for the stimulating effect caffeine has on the mind and body.

But does coffee give you more energy, or is it just placebo? Let’s take a look.

How Does Coffee Increase Energy Levels?

Research examining the effects of caffeine on performance and alertness has repeatedly shown that caffeine increases energy levels, mental acuity, and decreases feelings of both mental and physical fatigue [R, R].

After consuming a cup of coffee, caffeine quickly makes its way through the bloodstream and into the brain where it rapidly blocks the inhibitory neurotransmitter adenosine [R, R].

Adenosine is a neurotransmitter which is partly responsible for why we feel drowsy. When caffeine blocks adenosine, the body releases several neurotransmitters such as dopamine and norepinephrine in response which increase alertness and energy [R, R]. The rapid effect caffeine has on neurotransmitters is responsible for the increased memory, energy, reaction times and overall mental acuity experienced by those consuming caffeine [R, R, R].

Can Coffee Make You More Tired?

How caffeine affects a person’s energy levels is highly dependant on several factors, including genetics, the quantity of caffeine consumed, and frequency and time of consumption. Some people are “hypersensitive responders” to caffeine, while others find it has a milder effect [R].

It sounds counterintuitive that coffee may cause fatigue, but there are many anecdotal reports of people experiencing fatigue after drinking coffee regularly. But is there any research that supports the idea that coffee makes you more tired?

Caffeine Can Negatively Impact Sleep

Caffeine does increase energy levels, but this increase in energy can lead to insomnia, especially if caffeine is consumed in the afternoon. Research has shown that greater caffeine intake can increase the amount of time it takes to fall asleep and can decrease the total duration of sleep [R, R].

Because caffeine stays in the body for at least five hours on average (and up to nine hours), if you consume a cup of coffee in the afternoon, then this can result in difficulty falling asleep at night. [R]. Sleep deprivation is well-documented to be linked to higher levels of stress hormones, increased fatigue, and sub-optimal physical and mental performance [R].

According to research, smaller amounts of caffeine, when consumed in the morning, have little to no effect on sleep quality [R]. To ensure good sleep quality and minimal fatigue, stick with decaf or green tea in the afternoon.

Caffeine Can Lead to Dependency

Despite how widely used and socially accepted coffee is, caffeine is still a psychoactive drug that can cause changes to the neurochemistry of the brain.

So is coffee really addictive?

The evidence is mixed. One review concluded there is “sufficient empirical evidence to warrant inclusion of caffeine withdrawal as an official recognized psychological disorder [R]. According to another review, there simply isn’t enough evidence for caffeine to fit under the profile of an addictive substance [R].

The long-term consumption of caffeine will cause the brain to produce more of the inhibitory neurotransmitter adenosine as a means to compensate for caffeine constantly blocking it [R]. If one drinks coffee regularly for an extended period and suddenly stops cold turkey, caffeine withdrawal symptoms such as headaches and fatigue will persist until caffeine is reintroduced into the body [R].

A meta-analysis reviewing a total of 41 studies confirmed that although caffeine did increase energy levels for a few hours, participants in the reviewed studies reported feeling more tired the following day [R]. This implies that regular caffeine consumption could simply be alleviating caffeine withdrawal symptoms rather than actually increase energy levels.

The daily consumption of caffeine could potentially lead to behavioral addiction, which is different from physical addiction [R]. People get used to daily habits and routines with which their caffeine consumption is paired.

For example, someone can form a behavioral addiction to coffee if they drink coffee with their friend every day before work at a specific cafe. This is similar to how a smoker becomes behaviourally addicted to smoking as they smoke a cigarette after each meal.

How Much Caffeine is Safe to Drink?

Guidelines for caffeine consumption vary between different countries. The general consensus is that up to 400 mg of caffeine daily is a moderate and safe amount for adults, which is the equivalent to 2-4 regular cups of coffee per day [R].

It is also important to consider that different blends of coffee contain varying amounts of caffeine. In general, 2-4 regular cups of coffee will fall within the 200-400 mg range. Furthermore, certain life stages such as pregnancy increase the chances of adverse effects from caffeine, which is why the upper limit is set at 300 mg for pregnant women [R].

Summary

Coffee has been proven to increase energy levels in the short term. However, chronic coffee consumption can negatively affect your sleep and also result in a potential dependency both of which could lead to fatigue.

Coffee has an impressive list of health benefits outside of its effects on energy, however, it is important to monitor how coffee personally affects you and how sensitive you are to it in order to best assess how much you should be consuming.

If you are serious about making a real difference to your health and would like to work with a professional, then you can start by referring to our directory of aging clinics for guidance.

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. Information is provided for educational purposes. You should consult your doctor before acting on any content on this website.