A quick look on the net shows that that I'm not the only one thinking this way. Studies have shown that looking downwards in the way someone typically would increases the load on the neck and shoulder up to four times more than an upright posture. It is stretching the neck and spine and putting children particularly at risk of developing chronic conditions as they get older. Such a level of stress on children's necks hasn't been seen in this part of the world for 100 yrs when child labour had so many looking downwards on the work for hours on end! Compressing and inflaming the neck is causing occipital neuralgia leading to headaches.
So many of us are breaking our necks from hours of looking down at our phones and devices. Its time to get those heads (and phones) up into a better posture. Work on strengthening and keeping those neck muscles loose. Children should lie on the tummy more propped up on elbows when using devices to avoid over stretching their necks. Until the Google glasses are perfected, smart phones are with us for at least a a few years yet!