The light at the top of my phone is always flashing various colours. How do I know what they mean and how do I turn them off? It's Kitkat on Xperia Z2.
Not sure what the default colours are, but with an app called "Light Flow" on Google Play, you can change & add colours for almost any app or notification, or indeed turn all off as you are looking to do.
Navigate here. Settings - Display - Light effects. You can find various options on LED flashing.