To enable Wake-on-Bluetooth, you need to connect the device that you wish to wake the machine, and then:
That should allow your machine to Wake-on-Bluetooth. If the option to “Allow this device to wake the computer” is grayed out on the specific device, then you will need to check your Wi-Fi and Bluetooth adapter power settings and make sure you do not have the computer set to turn off them off when it sleeps. You can find this under each of their respective Power Management tabs in Device Manager, using the above steps. The “Allow this device to wake the computer” will remain grayed out on the Bluetooth adapter itself, even when everything is working correctly for your Bluetooth device to wake your computer.
If these power settings are all correct, and the option is still grayed out, then you may need to change a setting in your BIOS. It is also possible that your specific machine is not setup for Wake-on-Bluetooth. You may need to refer to the support or manual for your computer or mainboard for further assistance.