Coffee is one of the world’s most popular drinks. The morning beverage (or, for some, afternoon pick-me-up) is most known for its high caffeine content, perking up even the most tired eyes.

Given coffee’s popularity, several studies have examined its effects on your health, both immediate and in the long term.

As it turns out, moderate coffee consumption is associated with health benefits, including a reduced risk of prediabetes and liver disease. (1, 2).

Researchers have also looked into caffeine’s effect on your brain — and the findings so far look quite promising when it comes to your cognitive health.

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Coffee contains hundreds of bioactive compounds that contribute to its potentially powerful health benefits.

Many of these compounds are antioxidants, which fight the damage caused by harmful free radicals in your cells.

Here are coffee’s most important active ingredients (3):

  • Caffeine. The main active ingredient in coffee, caffeine stimulates the central nervous system.
  • Chlorogenic acids. These polyphenol antioxidants may benefit some biological pathways, such as blood sugar metabolism and high blood pressure.
  • Cafestol and kahweol. Present in coffee’s natural oil, these compounds are found in high amounts in unfiltered coffee.
  • Trigonelline. This alkaloid compound is unstable at high heat, and during roasting it forms nicotinic acid, also known as niacin (vitamin B3).

However, the amounts of these substances in a cup of coffee may vary.

Summary

Coffee can be a healthy beverage, packed with hundreds of biologically active compounds, including caffeine, chlorogenic acid, trigonelline, cafestol, and kahweol.

Caffeine affects the central nervous system (CNS) in several ways.

The effects are mainly believed to stem from the way caffeine interacts with adenosine receptors (4).

Adenosine is a neurotransmitter in your brain that promotes sleep.

Neurons in your brain have specific receptors that adenosine can attach to. When it binds to those receptors, it inhibits the tendency of neurons to fire. This slows neural activity.

Adenosine normally builds up during the day and eventually makes you drowsy when it’s time to go to sleep (5, 6).

Caffeine and adenosine have a similar molecular structure. So when caffeine is present in the brain, it competes with adenosine to bind to the same receptors.

However, caffeine doesn’t slow the firing of your neurons like adenosine does. Instead, it prevents the adenosine from slowing down neural activity.

Caffeine promotes CNS stimulation, making you feel alert.

Summary

Caffeine is the key reason why coffee boosts brain function. This stimulant blocks adenosine, an inhibitory neurotransmitter in the brain that makes you sleepy.

Caffeine can lead to an increase in resting brain entropy.

Brain entropy is vital to brain function, and high levels point to high processing abilities. An increase in resting brain entropy suggests higher information-processing capacity (7).

Caffeine also stimulates the CNS by promoting the release of other neurotransmitters, including noradrenaline, dopamine, and serotonin (8).

Caffeine may improve various aspects of brain function, including (9):

  • mood
  • reaction time
  • vigilance
  • attention
  • learning
  • general mental function

That said, you may develop a tolerance to caffeine over time. This means you will need to consume more coffee than before to get the same effects.

Keep in mind, however, that more isn’t always better. (10).

In fact, the Food and Drug Administration (FDA) has stated that healthy adults should only consume about 4 or 5 cups (400 milligrams) daily to avoid potentially dangerous or adverse side effects.

And if you are trying to become pregnant or are pregnant, breastfeeding, sensitive to caffeine, taking medications, or living with an underlying condition, you may want to speak with a healthcare professional.

Together you can decide what amount of caffeine is appropriate for you (11).

Summary

Caffeine causes changes in several neurotransmitters that may improve mood, reaction time, learning, and vigilance.

Coffee and caffeine may also affect your memory, but the research on this is mixed and more studies are needed.

Some studies suggest that caffeine may have a significant positive effect on both short-term and long-term memory (12, 13).

Other studies report no effects on memory or have even found that caffeine impaired performance on memory tasks (13, 14, 15).

In one study, when participants consumed a caffeine tablet after studying a series of images, their ability to recognize the images 24 hours later was strengthened.

Caffeine also appeared to make these memories more resistant to being forgotten, compared with the placebo group.

Summary

While some studies have found that caffeine may improve short-term memory, others have found no effect. The effects on long-term memory need to be investigated further.

The main reason why people drink coffee is to feel more energized and awake, so it’s no surprise that research has shown caffeine may suppress feelings of fatigue (16).

However, the energy boost only lasts for a certain amount of time before it starts to wear off. Then you may feel you need another cup.

Just make sure not to consume large amounts of caffeine in the late afternoon or evening, since it might disrupt your sleep at night (17).

If drinking coffee reduces the quality of your sleep, then it will likely have the opposite effect — rather than reducing fatigue, it may cause you to lose sleep and impair your overall brain function.

Summary

People often use coffee to counteract fatigue and tiredness. However, when consumed late in the day, caffeine may reduce the quality of your sleep and as a result make you feel more tired.

Alzheimer’s disease is the most common cause of dementia worldwide. It generally starts slowly but gets more severe over time.

Alzheimer’s causes memory loss, as well as problems with thinking and behavior. There is currently no known cure.

Interestingly, diet-related factors may affect your risk of developing Alzheimer’s disease and other forms of dementia.

Observational studies have associated regular, moderate coffee consumption with up to a 65% lower risk of getting Alzheimer’s (18, 19, 20, 21, 22, 23).

However, the protective effects of coffee and caffeine have not been confirmed by randomized controlled trials.

Summary

Consuming coffee regularly in moderate amounts is linked to a reduced risk of Alzheimer’s disease. However, higher-quality studies are needed to confirm these findings.

Parkinson’s disease is a chronic disorder of the CNS (24).

It’s characterized by the death of nerve cells in the brain that secrete dopamine and are important for muscle movement (25).

Parkinson’s mainly affects movement and often includes tremors. There is no known cure for this condition, which makes prevention particularly important.

Interestingly, studies show that coffee may help lower the risk of Parkinson’s disease (26, 27, 28).

A large review study reported a 29% lower risk of Parkinson’s disease in people who drank 3 cups of coffee per day. Consuming 5 cups didn’t seem to add much benefit, indicating that more is not necessarily better (29).

The caffeine in coffee appears to be the active ingredient responsible for these protective effects (30, 31).

However, it should be noted that while the evidence is substantial it is not 100% conclusive (32).

Summary

Consuming moderate amounts of coffee may protect against Parkinson’s disease. This effect is attributed to the caffeine.

When consumed in moderation, coffee can be very good for your brain.

In the short-term, it may improve mood, vigilance, learning, and reaction time. Long-term use may protect against brain conditions like Alzheimer’s and Parkinson’s.

Although many of these studies are observational — meaning they can’t prove cause and effect — they strongly suggest that coffee is good for your brain.

However, moderation is key. When consumed in excess, caffeine can cause anxiety, jitters, heart palpitations, and sleep problems (33).

Some people are sensitive to caffeine, while others can drink many cups per day without any side effects.

That said, some people definitely need to limit their caffeine intake, including children, adolescents, and pregnant people (34, 35).