User's Manual: Sleep

12 Surprising Sources of Caffeine

drinking-caffeine
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The caffeine crutch

By Sarah Klein

Overworked and sleep-deprived, more people are using caffeine as an energy crutch than ever before, experts say. That’s not all bad: In fact, 250 milligrams of caffeine per day—that’s two to three cups of joe—wakes up the brain, improves concentration, relieves stress, and may also help you live longer. But if intake is turning into addiction, you may notice side effects , including dehydration, trouble sleeping, anxiety, an upset stomach, and even problems during prenancy.

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