Whether it’s from coffee, tea, chocolate, or other sources, caffeine impacts your body in several different ways.
For many people, pouring a hot cup of coffee is a cherished part of their morning ritual. Not only does it taste delicious, but it can also give you an extra boost of energy to start your day.
So, it may come as no surprise that caffeine is among the most commonly used drugs in the world. It acts as a natural stimulant, meaning that it increases the activity in your brain and your nervous system. It also speeds up other bodily functions.
While caffeine can work wonders for productivity and performance in the short term, it may be best to use it with caution. Putting your body into a constant state of arousal can have harmful mental and physical health effects.
How caffeine affects the brain
Caffeine affects your brain.
For starters, the compound makes you more alert and gives you energy. In fact, that’s one reason why coffee is such a popular morning beverage.
Stephen Gilman, MD, a psychiatrist in Manhattan, explains that caffeine increases alertness, prevents drowsiness, and enhances cognitive performance. This means that if you consume a moderate amount of caffeine, you may experience increased focus and concentration.
But caffeine’s effects aren’t all positive. Even low amounts of the compound can increase anxiety and panic symptoms in people with anxiety disorders. There’s even a condition known as caffeine-induced anxiety disorder.
How caffeine affects the central nervous system
Research from 2021 shows that caffeine acts as a central nervous system stimulant.
Caffeine blocks the effects of adenosine, a neurotransmitter that relaxes the brain and makes you feel tired. It also elevates levels of blood adrenaline, also called the fight, flight, or freeze hormone.
Additionally, it increases brain activity of the neurotransmitters dopamine and norepinephrine.
“All these hormonal neurotransmitter changes stimulate the brain and promote a state of arousal, alertness, and focus,” Dr. Dia Smiley, a board certified cardiologist and internist at Columbia Irving Medical Center.
“Caffeine may cause anxiety feelings, given increases in heart rate or palpitations,” Smiley says. “Caffeine increases the production of cortisol, adrenaline, and norepinephrine, which are considered stress hormones and can cause the heart to beat faster and give you a boost of energy. This also causes patients to be jittery and can interfere with sleep.”
In adults, caffeine can last up to 8 hours — sometimes even longer. This is worth considering when you’re planning for sleep.
Caffeine may improve mood, decrease the likelihood of depression, stimulate brain function, and protect against Alzheimer’s and Parkinson’s disease, Smiley adds.
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How caffeine affects the digestive system
Caffeine can affect your digestive system in several ways.
According to a 2021 study, drinking coffee may provide beneficial antioxidant and anti-inflammatory effects in the gut. It may also have antiproliferative properties, meaning it could hinder the growth of harmful cells like cancer.
Additionally, it may offer pro-motility effects, meaning it can support healthy digestion.
In general, caffeine acts as a laxative and increases peristalsis — the muscle contractions that move food through your digestive system.
But that may not always be the case. According to Smiley, caffeine could also cause constipation by stimulating the production of stress hormones.
In addition, the compound can work as a diuretic to further contribute to constipation symptoms.
Caffeine may also increase the acidity in your stomach and the amount of stomach secretions. This can, in turn, lead to upset stomach, ulcers, and gastritis (i.e., inflammation of the stomach lining).
In fact, caffeine may worsen symptoms of the following conditions:
irritable bowel syndrome (IBS)
Some people also experience heartburn, nausea, vomiting, and diarrhea when consuming excessive amounts of the stimulant, Smiley says.
How caffeine affects the circulatory and respiratory systems
In some people, caffeine can cause high blood pressure and heart palpitations. Heart palpitations, or fluttering, is a feeling of your heart beating fast or irregularly.
“Heart palpitations occur because caffeine constricts the vessels and stimulates your central nervous system,” Smiley explains. “Although your heart has a spontaneous rhythm, nervous impulses can alter that rhythm.”
In particular, caffeine may worsen heart rhythm conditions such as:
supraventricular tachycardia (SVT)
premature ventricular contractions (PVCs)
Even if you don’t have a heart rhythm condition, you may be more sensitive to caffeine than others. Additionally, any sensitivity to caffeine can increase as you get older since caffeine lasts longer in your body as you age, Smiley explains.
How caffeine affects the skeletal and muscular systems
Caffeine is often found in pre-workout supplements. Many athletes consume these drinks before they exercise to reap caffeine’s energizing effects.
“Caffeine increases both aerobic and anaerobic exercise performance,” Gilman says. “This causes increased and improved sports performance secondary to increased endurance and the delay of onset of both muscle fatigue and central fatigue.”
A 2021 study found that caffeine consumption had a significant effect on mechanical activity in 40 professional male handball players. It affected both skeletal muscle contraction time and maximal displacement, meaning it could improve exercise performance.
But caffeine may not be great for your bones or muscles.
“Excessive caffeine can interfere with absorption and metabolism of calcium, which can cause osteopenia and osteoporosis — the thinning and weakening of bones,” Smiley says. “Excessive caffeine can also cause muscles to twitch. When stopping caffeine, caffeine withdrawal can cause achy muscles.”