At age 17, Baca would guzzle three to six high-caffeine, high-sugar energy drinks such as Monster, Rockstar or Red Bull every day to keep him awake through his 12-hour work shifts. "Didn't matter what kind," he said. "I drank them all."

It wasn't until ending up in the hospital that his buzz from energy drinks wore off for good. Baca went to the emergency room to have his appendix removed, which was directly related to his high energy-drink consumption, his doctors told him. He noticed signs, including gallstones, for about a year before ending up on the surgeon's table.

"I had anxiety attacks that would come out of nowhere — it's really hard to explain," Baca said. "But I was hard-headed and never went to the doctor."

Now he gets energy from plain coffee, and fruit.

"It wasn't just the caffeine that was doing it," Baca said. "It's the mixture of vitamins they put in there. Lately I've been eating fruit to stay awake. Did you know fruit gives you natural energy?"

Stories like Baca's are prompting schools worldwide to ban the energy drinks, which claim to improve performance, endurance and concentration. Yet doctors are warning they can cause serious medical problems with effects such as increased blood pressure, rapid heartbeat and increased anxiety. Schools in Pennsylvania, Massachusetts and Australia announced bans earlier this week.

Area retailers have noticed the increase in sales of energy drinks to kids after school, and some have placed restrictions on who can buy the drinks.

Roberts Oil Pump and Save of Moriarty has a strict store policy: no energy drink sales to anyone under the age of 16.

The policy began about four years ago, according to store manager Mary Marquez. Before then, kids coming from school would try to buy energy drinks, up to four at a time, she said.

"I heard about kids dying from them," Marquez said. "And ever since then I won't sell to young kids."

The Roberts Oil station in Mountainair has a similar policy. A random poll of area convenience stores revealed energy drinks are moving off the shelves here, like the rest of the country. Clerks said the majority of sales are to teenagers and young adults.

There are warning labels on many of the energy drinks, including "not recommended for children, pregnant or nursing women or people sensitive to caffeine."

However, the number of teenagers who admit they have a energy drink habit is on the rise. A 2008 market research report from Mintel revealed the energy drink market at retail is valued at $4.8 billion, which represents a 400 percent growth rate from 2003. Among teenagers, 35 percent said they regularly consume energy drinks, up from 19 percent in 2003.

The health effects of downing one too many have grabbed national headlines within the last few years. Ingredients found in the drinks, such as high amounts of caffeine, sugar and herbal stimulants, can have a variety of adverse effects, according to a recent article by Martha Grogan, M.D., specialist in cardiovascular diseases at Mayo Clinic.

"(Energy drinks) may cause a markedly faster heartbeat, irritability, nervousness, impaired sleep and nausea," Grogan wrote. "By itself, massive amounts of caffeine can increase your blood pressure and sometimes impair blood flow to your heart."

Some of the energy drink companies, such as Red Bull, claim the caffeine levels are similar to those of regular, drip coffee. This may be true, but the difference in energy drinks is the mixture of ingredients with caffeine, according to Amy Petersen, athletic trainer for Manzano High School. Petersen, who holds a bachelor's degree in athletic training and a master's degree in sports administration, believes the sale of energy drinks should be banned for anyone under the age of 18.

Some of the students she trains drink three to five per day, and she said they don't always understand how the drinks affect them.

"I don't think the kids realize exactly what they're getting," she said. "These drinks have the same effect as caffeine, but in some of the stronger ones they're getting double or triple the effect."

Petersen sees firsthand the effects multiple energy drinks have on children, and hopes more limits in stores and schools are the near future.

"Sometimes when they're running a lot, they tell me, 'My heart's racing, it feels like it's going to explode,'" she said. "Even, 'I'm having a heart attack.' There could come a day when it actually happens."