Note
This is a post from 2014, please check if it still applies, at the time of writing bumblebee was relatively new.
I had some problems with bumblebee and optirun command --- it just suddenly stopped working.
So here is how to switch your computer to use nvidia on debian, and use nvidia proprietary drivers
Remove bumblebee
Install Nvidia proprietary drives (https://wiki.debian.org/NvidiaGraphicsDrivers).
Note
Remember to configure xorg.conf precisely as in the instructions.
Restart. Go to bios and switch off integrated graphics card.
If you restart your computer before step 3, most probably your X will not be usable.