The vast majority of cryptocurrencies take advantage of blockchain technology. In their most simple form they use cryptography to process transactions and create new coins, this process is usually performed by computers solving complex equations and is called mining. All processed transactions are stored on the blockchain which acts as a giant computerized ledger.
Limited trading hours help to reduce volatility in stock prices but also limits the liquidity of stocks. When trading hours are shorter more news reports and earnings reports are published while the markets are closed. As a result, investors have more time to process new information and general make fewer knee-jerk reactions. Read more about how trading hours vary around the world.