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.
The four suits of a pack of cards. 4: full of symbolism. If you count up the numerical value of a whole pack of cards â reckoning on 11 for a jack, 12 for a queen and 13 for a king â you reach 364, which with the addition of one for the joker makes 365, the number of days in the year.