Nightshift workers, students during finals and new parents all have one common love: caffeine.

From morning coffees to mid-day energy drinks, caffeine is an American dietary staple — and it’s found in more places than you think.

“People only think of caffeine in coffee or soda, but it can also be found in things like chocolate, energy drinks, many teas, over-the-counter medications like Excedrin and even e-cigarettes,” says Paul McFarlane, MD, a primary care provider and hospitalist for Hartford HealthCare in Norwich.

We asked Dr. McFarlane to break down the benefits of caffeine, and how it affects our overall health.

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6 benefits of caffeine on your body.

About 80% of Americans take in some form of caffeine every day, many for the jolt of energy it gives. Dr. McFarlane explains how caffeine hits different parts of the body, including:

  1. Delaying sleep. Caffeine counteracts receptors in the nervous system that promote sleep, making us more alert.
  2. Increasing attention and mental performance. Caffeine increases the release of dopamine and norepinephrine, which improve focus and cognition.
  3. Elevating mood. It also increases serotonin levels, along with dopamine, which result in that uplifting feeling.
  4. Increasing arousal. Your central nervous system is stimulated by caffeine, speeding signals between your brain and body.
  5. Helping with muscle contractions. This boosts physical training endurance, speed and strength by interacting with the body’s calcium channels.
  6. Elevating heart rate. Through interaction with various chemicals, caffeine can increase the heart rate.

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Sounds great. So what’s the problem with too much caffeine?

There can be too much of a good thing.

Too much caffeine can have a negative impact on the body, Dr. McFarlane notes.

These include:

  • Insomnia
  • Jitters and anxiety
  • Increases (or drops) in blood pressure
  • Issues with digestion
  • Dehydration
  • Racing heart (tachycardia).
  • Break down of muscles

“Fortunately, it’s not common to see toxicity or death from caffeine, but the body does feel the impact when too much is taken in,” he says.

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Caffeine worsens some medical conditions.

Certain health conditions tcan be aggravated by caffeine, such as:

  • High blood pressure.
  • Acid reflux disease (GERD). Caffeine impacts the muscle associated with the esophagus.
  • Insomnia. Avoid caffeinated products within six hours of planned sleep.
  • Overactive bladder. Caffeine affects muscles lining the bladder, causing the need to urinate more.
  • Pregnancy. Pregnant women should limit caffeine to 200mg a day.

Caffeine hangovers are real.

If you’re trying to limit caffeine – or just run out of coffee or soda – you’ll likely experience withdrawals, Dr. McFarlane notes.

“Caffeine is a substance and withdrawal from it can have significant impacts. It’s an actual clinical diagnosis,” he explains.

That diagnosis hinges on having at least three of the following symptoms:

  • Headache
  • Fatigue or drowsiness
  • Depressed mood
  • Irritability
  • Difficulty concentrating
  • Flu-like signs

So, how much caffeine is too much?

There are a number of factors that affect how much caffeine you can have without negative effects. These include:

  • Tolerance
  • Sensitivity
  • Metabolism

But in general, no one should consume more than 400mg of caffeine a day, Dr. McFarlane says.