It is very easy to restart the Xperia Z. Just hold power and Volume Up buttons for about 15 seconds. Your device should vibrate 3 pulses in a row, It should now be off, and don’t plug it in anywhere. xperia z pros and cons   That’s all to it, very simple.  If you want to avoid doing this everytime, just to restart.  Then consider rooting and flashing a custom rom , as most custom roms have a restart option in the power button menu.