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When a coffee fanatic doesn't get that fix, blood flow in the brain spikes, according to a recent study in Psychopharmacology. This expansion of blood vessels results in a headache, while you suffer from other nasty symptoms such as fatigue and grumpiness. To avoid this, you visit the office java pot or duck out to grab a cup.
WHY IT'S BAD: A constant infusion of joe can set your nerves on edge. "High daily caffeine intake may decrease hand steadiness and increase anxiety," says Russell Keast, Ph.D., a caffeine-consumption researcher at the School of Exercise and Nutrition Sciences at Deakin University in Australia. Then there's a study from Dartmouth Medical School that found that people who consumed 400 milligrams of caffeine a day (the amount in about four eight-ounce cups of coffee) for an entire week showed a 35 percent decrease in insulin sensitivity, which may up the risk of diabetes.
BREAK THE HABIT: Start by writing down every single thing you eat or drink for a few days to identify all the sources of caffeine — soda, coffee, tea, and energy drinks are common culprits — then tally the total number of milligrams you're consuming, says Chad Reissig, Ph.D., a Johns Hopkins University researcher who studies caffeine's behavioral effects. (You can find the actual amounts on beverage manufacturers' websites.) Then set out to reduce your caffeine intake by about 10 percent. "You can also mix decaf with your cup of full-strength coffee and slowly increase the ratio," says Reissig. Keep dialing back by 10 percent every few days until your craving subsides.
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Cranking the Tunes
This is a habit that sneaks up on you: You listen to your music through your headphones at a higher volume than you should, and eventually your ears get used to it. Then you play it at that level all the time. "It's possible to become accustomed to louder and louder sounds without realizing it," says Robert Fifer, Au.D., director of audiology and speech-language pathology at the University of Miami's Mailman Center for Child Development.
WHY IT'S BAD: Blasting Beyonc? at full volume through earbuds for long intervals can result in permanent hearing damage, because your body lacks a self-defense mechanism for loud noise. While you won't feel pain in your ears until the volume exceeds 120 decibels, the damage can begin much earlier than that. The reason: The cells in your inner ear that process sound begin working overtime to keep up with the onslaught. Eventually, they die off under stress, Fifer says. You may also experience a constant ringing in your ears, called tinnitus.
BREAK THE HABIT: You have to retrain your brain to perceive lower volume levels as normal, and to automatically tune out background noise. Start by turning down the volume on your iPod or car stereo until you can hear people who are talking to you. "When you force yourself to listen to music at a lower level, your brain will begin to perceive it as normal after about a week," explains Catherine Palmer, Ph.D., the director of audiology at the University of Pittsburgh Medical Center Eye & Ear Institute.
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