Healthy Diet

Is Caffeine Bad for You? Here’s What Research Says

  • Caffeine is considered the world’s most widely consumed psychoactive substance and is found in coffee, tea, sodas and energy drinks.
  • Studies confirm that healthy adults can safely consume up to 400 mg of caffeine in a day.
  • Caffeine offers both benefits and drawbacks.

Coffee is just the thing to kickstart your day. You’re probably familiar with that warm feeling you get when sipping a freshly brewed cup. Caffeine, which is an active ingredient in coffee, can provide benefits such as improving focus and alertness (1), as well as your energy levels — which is perfect for waking your senses up in the morning or to give you that boost you need to complete your tasks. It can also help improve physical performance for athletes (2). However, this is something that not everyone agrees on. Some argue that the negative effects of caffeine outweigh its benefits. Is caffeine bad for you? Here’s what we’ve found.

pile of coffee beans

What is Caffeine?

Caffeine is considered the world’s most widely consumed psychoactive drug (3). It’s a common compound of coffee and tea. It’s a central nervous system stimulant, which means it helps increase the activity of your brain and your body. Caffeine staves off fatigue by opposing the action of adenosine – the body’s natural signal for sleep. As adenosine builds throughout the day, the desire to sleep, also known as “sleep pressure,” increases. Caffeine counteracts these natural signals, reducing the feelings of sleepiness. This doesn’t mean you can avoid sleep, though. You’re merely masking the body’s natural sleep signals.

cup of tea is caffeine good for you

Caffeine is one of the main ingredients in most sodas and energy drinks.

Does Caffeine Offer Health Benefits?

Studies say healthy adults can safely consume up to 400 mg of caffeine in a day. That’s equivalent to roughly four cups of brewed coffee, 10 cans of soda or two shots of energy drinks. (You wouldn’t want to consume this much anyway, due to their negative health impact.) Now, if you consider caffeine as is (without sugar and artificial sweeteners), then that could be fine and you might be able to take advantage of its benefits.

It Could Improve Focus

For instance, caffeine can improve attention span and information processing. It can also boost your metabolism, helping your body burn more fat (4). This might be a logical reason to enjoy a midday cup of tea or coffee at work. It could possibly help you function more efficiently when you’re starting to feel that afternoon slump.

Caffeine Might Help Your Gym Sessions

Caffeine can improve endurance (5) and anaerobic performance (6). This means it can help you work out for longer periods of time, possibly making a caffeinated beverage a great pre-workout refreshment.

So, caffeine in and of itself offers many benefits.

man running on forest trail

Is Caffeine Bad for You, Too? Some of the Negative Effects…

Like most things, caffeine also has some downsides.

It May Disrupt Sleep and Cause Insomnia

Your body needs sufficient rest, and studies show that taking caffeine six hours before bedtime has disruptive effects on sleep (7). Consumption of caffeinated drinks may also cause insomnia (8).

It May Trigger Headaches

Are you familiar with the term “weekend migraine attacks”? It’s the type of headache that a lot of people feel during the weekend (even if they did not drink the night before). There are studies that show a connection between caffeine intake and the weekend migraine.

Although there are other factors that contribute to this occurrence — such as sleep hygiene — caffeine withdrawal is one of the most common reasons behind it (9). During the weekdays, people tend to consume more caffeinated drinks to help prevent drowsiness. The weekends, on the other hand, are more laid back, and so people consume less caffeine. This leads to withdrawal symptoms, like headaches.

people drinking coffee with caffeine

It May Cause Palpitations

Palpitations are when your heart is pounding, fluttering rapidly or skipping beats. One of the causes is consuming caffeine (10), especially if you’re not used to it.

It Can Increase Anxiety and Depression

A study performed on 234 students in Daegu, Korea showed that high caffeine intake was associated with lower academic achievement and greater odds of having significant depression (10). This may be an effect caused by caffeine’s tendency to cause sleep problems.

It May Raise Blood Pressure

One study shows an increase in blood pressure levels on people with hypertension that consume caffeine (11). However, people who regularly drink caffeine develop tolerance to it in the long run.

Clearly, there are pros and cons when it comes to consuming caffeine. Some caffeine in your diet could be good for you, but the key is moderation. If you’re unsure about whether or not you should continue with your intake, it’s best to talk to your doctor about it.



  1. “Effect of Caffeine on Attention and Alertness Measured in a Home-Setting, Using Web-Based Cognition Tests”, Pasman, W., et al., (2017).
  2. “Correction to: The Effect of Acute Caffeine Ingestion on Endurance Performance: A Systematic Review and Meta-Analysis”, Southward, K, et al., (2018).
  3. “Is caffeine addictive? The most widely used psychoactive substance in the world affects same parts of the brain as cocaine”, Daly, JW., et al., (1998).
  4. “Metabolic effects of caffeine in humans: lipid oxidation or futile cycling?” The American Journal of Clinical Nutrition, (2004).
  5. “Effects of caffeine ingestion on metabolism and exercise performance”, Medicine and Science in Sports, (1977).
  6. “Caffeine and anaerobic performance”, David, J.K. and Green, M., (2009).
  7. “Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed”, Drake, C., et al., (2013).
  8. “Caffeine consumption, insomnia, and sleep duration: Results from a nationally representative sample”, Chaudhary, NS., et al., (2016).
  9. “Influence of caffeine and caffeine withdrawal on headache and cerebral blood flow velocities”, Couturier, EG., et al., (1997).
  10. “The Relationship of Caffeine Intake with Depression, Anxiety, Stress, and Sleep in Korean Adolescents”, Mi-Joo, Jin, et al., (2016).
  11. “The effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals: a systematic review and meta-analysis”, Mesas, AE., et al., (2011).