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.
A standard deck of playing cards has 52 cards in it broken into 4 suits of 13 cards each. Each suit has 3 face cards (a King, a Queen, and a Jack) so 4 suits multiplied by 3 face cards equals 12 face cards in a standard deck of cards. Face card - Wikipedia.