Digital devices can hurt you if you don't use them properly. The culprit typically is a repetitive strain injury, sometimes called a cumulative trauma disorder, which can be caused by excessively repeating the same motion or non-motion. Because PCs and other digital devices can be so captivating, spending long times with them is common.

Whether it's typing furiously on a smartphone, mousing your way around word-processing documents and websites, tapping a touchscreen on a tablet, or sitting in the same position in front of a laptop, if you do it long enough, you put your body at risk.

Even if you haven't yet experienced a sore wrist, shoulder, neck, back, or eyes, you should give some thought to how you position yourself. Good ergonomic equipment helps, but according to experts, your work habits are just as important. Here are some tips:

1. Take frequent breaks. Gimme a Break and Auto Timer are free extensions to the Google Chrome and Mozilla Firefox Web browsers, respectively. Each periodically reminds you to take your eyes off the screen. Alternately, you can buy an old-fashioned kitchen timer and set it to remind you to take breaks.

2. Sit at a desk. This is better for your back and neck than sitting on a cushy sofa or lounge chair. While at a desk, sit up straight with your shoulders and head back, your feet flat on the floor or on a footrest, and you forearms parallel to the floor.

Ergonomic chairs that are adjustable in multiple ways can go a long way in preventing back problems. Recommended high-end brands include Aeron from Herman Miller, Leap from Steelcase, and BodyBilt by ErgoGenesis. You also can find adjustable ergonomic office chairs at your local office supply store, such as Staples or OfficeMax, that range from pricey to affordable. Being able to sit in a chair, play with its controls, and evaluate the seat padding can help determine whether that particular brand and model is right for you.

3. Better yet, stand - or even walk - at a desk. Sitting too long in even the best chairs can lead to stiffness and other problems. Working while standing is a viable solution for some. Sitting/standing desks, also called height-adjustable desks, height-adjustable workstations, and hi-lo desks, cost from $300 for low-end manual adjust to $3,000 for high-end electric adjust. Alternately, you can fashion your own set-up for under $25 by placing a small end table that's big enough for a laptop or tablet on top of a desk.

Some intrepid users swear by treadmill desks, where you walk while working. Here, too, you can buy or build yourself.

4. Position your keyboard and mouse. To prevent wrist problems when using a keyboard, keep your wrists straight. Make sure your keyboard is the appropriate distance from you to allow for this. With a mouse, try to keep it as close to the keyboard as possible, to prevent shoulder problems from having to reach for it. A touchpad built into a keyboard is even better.

5. Protect your eyes. Eyes are another common sore point when computing. Experts say the most eye-friendly moves are to stay a foot and a half away from the monitor

and minimize screen glare by positioning external lighting to the side, rather than in front or behind. Also, periodically give your eyes a rest. Look away from the screen every 20 minutes or so for about 20 seconds, or close your eyes for the same amount of time.

Along with the above, stretching, exercise, and massage can help keep your body healthy. Computers and other digital devices are great, when they're not a pain in the neck, the back, the wrists, the eyes ...