Stiff neck

What causes it: Holding your head in an awkward position for an extended period of time—while using a smartphone or laptop, say—can strain your neck muscles, leading to pain and stiffness.

What to do: Be aware of your posture. If you work in an office, make sure your desk, chair, computer keyboard, and monitor are positioned to let you work comfortably.

The same rules apply at home. "The best way to use a laptop is on a desk, not your lap, with the screen at eye level and the keyboard within easy reach," Dr. Raj says. And that goes for iPads and other devices, she adds.

If your stiff neck doesn't respond within a week to home remedies like over-the-counter pain relievers, heating pads, icing, or gentle massage, check with your doctor.