Not enough sleep or disruptions to the sleep-wake cycle (such as those that may occur with shift work or travelling to a different time zone) cause the physiological state known as fatigue. Staying awake for 24 hours leads to a reduced hand-to-eye coordination that is similar to having a blood alcohol content of 0.1.
There are 13 hearts in a standard 52 card deck. There are also 13 diamonds, 13 spades and 13 clubs.
Bats only have 6 health = 3 hearts. Difficulty modes: Similar to the game mentioned above as difficulty grows the text to your right will change. It is a graphical feature, that actually has nothing to do with the way it works - just a notification for the player.