|For the condition in Fallout 3 and Fallout: New Vegas, see Well Rested.|
You had a great sleep, and feel alert and invigorated! +10% XP earned for a limited time.”
Well Rested is a temporary perk in Fallout 4. The Well Rested effect is no longer a condition, but now a temporary perk and is obtained much the same way as before but can be earned by sleeping in any bed, purchased or unowned.
After sleeping in a bed for a good amount of time, earn +10 XP earned for 8 hours.
If sleeping while in the company of a companion you're in a romantic relationship, the Sole Survivor will receive the Lover's Embrace perk instead of Well Rested.