Hi @absolutebeginner,
I'm sorry to hear this. As @uliwooly suggest you can reboot your device to safe mode to see if this behavior is caused by one of you downloaded apps as these will be temporarily disabled in this mode.
If you are still experiencing the same behavior I recommend that you reset Xperia Home, note that this will reset your home screen to the default screen. You can take a screenshot of you home screen so you can restore it, to do so press and hold volume down and the on/off key simultaneously.
To reset Xperia Home go to: Settings > Apps > Tap ... > Show system > Xperia Home > Storage > Clear data > Ok. Then restart your device.
Let us know how it goes.
