Deep Sleep

 is a perk added to Fallout 3 with the Broken Steel add-on.

You sleep deeply no matter where you are. You get the Well Rested benefit of +10% XP for eight hours no matter what bed you sleep in.

This perk comes to be completely useless, unless you have the Swift Learner perk at level 3 and want to increase gaining of experience even more.

Taking Swift Learner instead of this grants you permanent 10% exp boost with no matter of sleeping, and you don't lose your ability to sleep in the bed you own for additional boost.