In the upper left corner of the screen, you’ll have two bars, a health bar and a rested bonus bar. Keep an eye on both while you’re playing. If your health runs out - you die - and you can either restart the level or respawn at your current position for a nominal cost. Time spent away from the game accumulates into "rested experience" . You can determine how much of a rested bonus you have accumulated based on the golden glow on the Rested Bonus bar. You will be given the extra experience points you have accumulated as a bonus (it will say (+ # bonus) on the experience pop ups as you play) until it's all used up.