wake computer from sleep using keyboard?

Hi all, I have a Studio 15 laptop which I bought a few weeks ago. Ild like to be able to - once the laptop is asleep - be able to wake it just by pressing a key on the keyboard (at teh moment I have to reach around to the power button on the side). How can I do this? Ive been into device manager, selected keyboard and gone to properties, but theres no power management tab for the keyboard. Im looking for the checkbox 'use this device to wake laptop' (or whatever the exact wording is). Can anyone help with this matter?

many thanks