If you lean forward into the position you're in when you're looking at your phone, take note of the position of your head and neck, along with how far from upright you're bending forward. Notice the pulling you feel in the muscles around your neck, upper back, and shoulders. We're all built to move that way, sure, but sit like that for a couple hours and you're going to feel some long-term aches and pains.
According to Dr. Kenneth Hansraj, a New York spinal surgeon, that position puts an added 60 pounds of pressure on the spine. Held upright, our heads weigh between 10 and 12 pounds. It's when you started leaning forward — and staying like that — that the added pressure builds up and can cause all kinds of problems in your spine and muscles. Dr. Hansraj says that he's even seen people get to the point where that position was at the heart of a problem that needed surgery to fix, and if that isn't enough to terrify you into sitting up straight, nothing will be.
In more common parlance, text neck is becoming more and more common even in the youngest segment of cell phone users. Specialists at the Cleveland Clinic say that the global position of checking your phone can cause a huge number of other problems, too, like even restricting the space your lungs have in your chest cavity, which forces them to work harder to pull enough oxygen into your body. Your heart has to work harder, too, while your neck and shoulder muscles contract. It's the domino effect of bad posture, and given how distracted we usually are by our phones, it's probably one that we don't even notice until it starts causing problems.