1/14 Light Bulbs
When all you have is natural light, productivity is limited to daylight hours. Light bulbs completely changed the world, allowing people to be active after dark. Though Thomas Edison gets most of the credit for the invention of the light bulb, this invention was the collective work of Thomas Edison and Joseph Swan, along with some two dozen people who were instrumental in creating incandescent lamps throughout the 19th-century. Edison is credited as the primary inventor because he created a completely functional lighting system, including a generator and wiring as well as a carbon-filament bulb in 1879.
In addition to the introduction of electricity into homes throughout the Western world, the light bulb had an unexpected consequence - it changed people's sleep patterns. Instead of going to bed when darkness fell and sleeping in segments throughout the night separated by periods of wakefulness, we now typically stay up except for the 7 to 8 hours allotted for sleeping.