By Heather Brown

MINNEAPOLIS (WCCO) — We all love our caffeine, espcially sleep specialists like Dr. Mike Howell.

“I usually have a shot of espresso, and then about two or three cups of coffee later throughout the day,” said Howell, a neurologist at the University of Minnesota.

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He says you are OK with caffeine up to about 400 milligrams. Here is another way to look at that: It’s 10 cans of soda, or two 16-ounce cups of coffee, or two-and-a-half cans of energy drink.

“It’s a lot,” Howell said. “Caffeine is the most commonly consumed drug in the world.”

Ninety-percent of Americans consume some of it each day.

(credit: CBS)

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“It’s a substance that’s acting on our nervous system,” Howell said. “As you go about your day, your brain is building up a compound called adenosine. As adenosine builds up over the course of the day, you get sleepy. Caffeine blocks the effects of adenosine on your brain.”

It has benefits.

“It improves your alertness and your reaction time,” he said.

And drawbacks

“Caffeine in excessive amounts can be bad for you, especially if you have heart problems, especially if you’re prone to anxiety or if you have difficulty sleeping,” Howell said. “I think it’s OK to drink caffeine in moderation. I would not drink more than three to four cups a day, even myself.”

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Our expert says we should also be conscious of what else is in our drinks — especially the sugar in soda, energy drinks and sometimes coffee. And consider the vitamins and minerals you’re not getting if you’re replacing them with so much caffeine.

Heather Brown