Canadians spend more than six hours a day looking at smartphones, TVs, tablets and computers. But all those screens are taking a big swipe at our health; in one recent U.K. study, 84 percent of hand-held device users between the ages of 18 and 24 reported pain in at least one body part.

This is no surprise, says Vancouver physiotherapist Carol Kennedy. "People sit at the computer at work all day, then they come home and get on the couch with a tablet to surf the Internet, and in between, they're talking and texting on smartphones," she says. "All that device use adds up."

Just what can it add up to for you? Watch for these tech-related health issues:

Text neck
A smartphone user sends and receives an average of 764 texts a month, according to a Nielsen consumer report. All that time with your head tilted forward puts you at risk for developing "text neck," a musculoskeletal (MSK) condition that may cause headaches, plus neck, shoulder and upper-back pain.

Think of your head as a big bowling ball on your shoulders, says Margo Fraser, a Calgary-based Canadian certified professional ergonomist. "When the neck bends forward as we lean into our devices, the shoulders have to support the weight of our heads, increasing the stress on the muscles," she explains. Hunching over your phone with your head at a 45-degree angle can increase the pressure on your spine from about 10 pounds to 49 pounds, according to a study by New York spinal and orthopedic surgeon Dr. Kenneth Hansraj.

Prevent it! Avoid tucking your chin more than 20 degrees toward your chest when you look at your screens, says Kennedy. So if you're looking at your device in your lap, your head is tilted too far forward.

Texting thumb
If you're a prolific texter, your thumbs might ache. The carpometacarpal joint at the base of the thumb is prone to osteoarthritis, a wear-and-tear degeneration and inflammation that occurs as cartilage wears away. The repetitive motion of texting and gaming may also make wrist and thumb tendons sore.

Prevent it! Use both thumbs to text; single-handed texting while holding the phone in the same hand puts additional stress on the joint. "Texting quickly with fewer pauses also leads to more symptoms, so go slow and take breaks, or limit the time spent texting," says Kennedy.

Mouse finger
Spending hours at a computer can lead to a variety of MSK conditions, related to prolonged fixed positions or repetition. "Mouse finger," for example, is caused by repeatedly using the same finger on the mouse, says Fraser. Your shoulders can also ache if your keyboard is wider than they are or if you have to reach too far for the mouse.

Prevent it! "Sometimes, you have to change the mouse to the other side for a while, or use a tilted mouse or some forearm support," says Kennedy. A tablet-and-stylus setup (like the Wacom systems) can eliminate clicking altogether. If possible, get an ergonomic assessment of your workstation. And take breaks. At least once an hour, get up and move around for up to five minutes, says Fraser. 

Sleep disturbances
Watching TV, texting friends and checking email before bed can lead to a lousy night's sleep—and 95 percent of those surveyed by the U.S. National Sleep Foundation used some form of technology within an hour of bedtime. That keeps you from disengaging and clearing your head before sleep, warns Dr. Adam Moscovitch, medical director of the Sleep and Fatigue Institute in Calgary and Toronto. Plus, the blue light from LED screens hinders the release of the sleep hormone melatonin, making it harder to drift off and have a restorative deep sleep.

Prevent it! Avoid using electronic devices within three hours of bedtime. Not possible? Filter out the blue light with a screen protector, or use apps, such as Twilight or Night Filter, that gradually shift the tone on your screen as night falls, or wear specially designed orange eyeglasses.

Digital eyestrain
You view your smartphone, tablet or laptop at a "reading" distance, which can be tiring for your eyes. Focusing for too long can strain our eyes, explains Dr. Ken Roberts, a Fredericton ophthalmologist. Prolonged focusing may also lower your blink rate, causing dry eye, which makes your eyes burn and water.

Prevent it! Eyestrain usually sets in after two hours of device use, so watch the clock. "If you feel tension in the brow area or pain and pressure behind the eyes, that's a sign that your eyes are tired and need a rest," says Dr. Roberts. "Take a 10- to 15-minute break and do something that doesn't require near vision." Increasing your screen's font size and using artificial tears to moisturize the eyes may also help.