Thanks Mathew, your post inspired me.
It also works for me with I remove the mouse dongle, but obviously that's not so practical.I looked at the mouse settings in the device manager and Allow this device to wake the computer was already unchecked, so I searched again in Bing and found the following command:
powercfg -devicequery wake_armed (run as admin)This showed me 2 USB Root Routers.
I went into the device manager and unchecked Allow this device to wake the computer for both of them and even after a reboot it seems to work.
My laptop now sleeps like a baby
Thank you for this