The authors say that effects of caffeine can build up over time and lead to measurable changes in the brain: If you’re blocking adenosine receptors with caffeine over the long term, this can result in “adaptive changes and lead to chronic alterations of receptor expression and availability,” the authors write.

Long-term effects at this level may include chronic insomnia, constant anxiety, depression, and stomach problems. It can also cause high blood pressure or make high blood pressure worse.

What does caffeine do to your body? Caffeine is well absorbed by the body, and the short-term effects are usually experienced between 5 and 30 minutes after having it. These effects can include increased breathing and heart rate, and increased mental alertness and physical energy.

Caffeine is a stimulant that increases alertness and enhances concentration in consumers. However, regular ingestion of the drug alters the brain’s chemical makeup, and can cause fatigue, headaches, and nausea when attempting to quit.

Caffeine consumption is generally considered safe, although habit forming. Some side effects linked to excess intake include anxiety, restlessness, tremors, irregular heartbeat, and trouble sleeping ( 53 ). Too much caffeine may also promote headaches, migraine, and high blood pressure in some individuals (54, 55 ).

Here are a few tips to turn your coffee from healthy to super healthy.

1. No Caffeine After 2 P.M.
2. Do Not Load Your Coffee With Sugar.
3. Choose a Quality Brand, Preferably Organic.
4. Avoid Drinking Too Much.
5. Add Some Cinnamon to Your Coffee.
6. Avoid Low-Fat and Artificial Creamers.
7. Add Some Cocoa to Your Coffee.

Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. That’s roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two “energy shot” drinks.