Been trying to set up my phone so I could double tap to make it sleep and I finally figured out a way.
You'll need two things, a launcher that supports assigning an app to "double tap" (novalauncher does this). It will simply launch said app when you double tap anywhere on the launcher.
Second thing is this app: https://play.google.com/store/apps/d...ockscreen.free
All you have to do is assign this app to the double tap in the Novalauncher settings and bam, double tap to wake and double tap to sleep now enabled.
Just thought I'd share this because I know it's a feature everybody wants.