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.
In a standard deck used for bridge, poker and other games, there are 52 cards (4 suits, 13 cards per suit). There are also two jokers, because some card games use one or two jokers in the game. So sometimes you could say there are 54 cards in the deck, even though most card games don't use the jokers.