My Windows 7 laptop and Windows 8 Surface Pro kept waking up from sleep while in my bag and causing it to heat up and drain the battery. So I ran the following command in command prompt:
This told me the last device that woke my laptop up, it was wuauserv. Windows Update. Change Windows Update to anything but Automatically download and install updates. I changed mine to manually install.
If nothing shows up from running the command above then have a look at other devices that might be set as an option to wake up the computer.
Running the following command will show which devices are set to “Allow this device to wake the computer”
powercfg -devicequery wake_armed
Un-tick the the “Allow this device to wake the computer” box for for devices shown above in device manager.