A few years ago, a computer game by the name of
Crusader: No Remorse was fairly popular. One of the things that attracted me to it was its story line. The entire world was run by one large
multinational corporation, which supplied the consumers, ran all industries, was the
government, and employed the entire populace of the
Earth, and the
Moon. Its opposition was a handful of rebels.
One of the best parts of the game was the story line. The citizens depicted within the game were drones. 16-18 hour work shifts. 92% income tax rate. These people didn't know any better, they just lived as they were. They were raised believing that the human body only needs 4 hours of sleep per night, and that 16-hour shifts was the amount of time for work that yields maximum productivity.
If we increased the amount of hours in the day, what would happen? We'd just die quicker.
We'd be working longer hours. If there were 36 hours in a day, you wouldn't sleep 8 hours, work 8 hours, and have "free time" for the remaining 20 hours. It'd be proportional to what it is now. In fact, since you now should have 12 hours of uninterrupted sleep, that could be seen as grounds for working longer shifts. The 16-hour shifts as seen in Crusader would become a reality. The long-term effects of working oneself out in such a manner are evident: more stress, which leads to chronic illnesses, which leads to shorter life spans.
More hours in a day wouldn't give you more free time. You'd probably get the same amount of free time, work yourself harder, and die quicker.