Shortcut to sleep

Hi
how do i highlight the sleep button (restart, shut down) in the login page without using my mouse. There is different people using my imac and when i put it to sleep by pressing command-option-eject who ever activates it is brought to my account.
Is there a shortcut to logout and sleep at the same time.
Regards Greg.

Got it all by myself.
Press "control-F7" to highlight buttons then tab to select sleep.
Not exactly the shortest shortcut but it answers my question so I don't have to use the mouse.
Still looking for a way to logout and sleep at the same time (a real short cut ).
Thanks man your fantastic.

Keyboard shortcuts in OS X | creativebits

"Option-Command-Eject or Option-Command-Power" = Sleep

Whats going on with my mac.
The keyboard shortcut "option-command-eject" puts it to sleep for about 3 seconds then it starts up again. I looked up possible causes but my problem seem to be only with that shortcut (so far). I reset SMC and took batteries out of mouse and still not working. Is it a hardware issue? Any other ideas whats wrong? Again it only happens when I activate sleep by pressing "option-command-eject". It sleeps perfect when selected from the menu bar.
This is driving me absolutely crazy, someone please help

Funny you should mention that. Ever since I installed 10.6.6 I've had either the same problem as yours or difficulty in going to sleep whether I use the mouse or keyboard. Any ideas? PS. I've also tried Control + eject + s. It works, but very slowly.