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 52 playing cards consists of 4 suits, with 13 kinds in each suit. In many card games, the kinds are ranked, and are often referred to as the ranks of the cards. In some games, the suits are also ranked. In the picture above, the four rows are the four suits.