Sometimes not knowing why youre itchy can be as irritating as the symptom itself. But new science is uncovering some surprising reasons youre scratching—and hope for new relief.

1. Stress. German and Canadian researchers found that loud sounds stimulated the immune systems of mice, making them itch. You may react the same way to stress, so stress relievers like yoga or meditation could make your itch disappear.

2. Cell phones. Rashes are popping up on the faces of people who rack up long hours on their mobiles, according to British research. The culprit is nickel, a metal that frequently causes allergic dermatitis. Solution: Use an earpiece or the built-in speakerphone to keep the nickel away from sensitive skin.

3. Quaternium-15. This preservative is found—in varying amounts and by many different names—in nail polishes, self-tanners, sunscreens, and many kinds of makeup. If a product bothers you, experts say Q-15 may be the culprit. Try sampling different brands until you find one that suits you.