How much sleep did people 100 years ago get?

The expectation is that we sleep about 20% less then 100 years ago. This is due to the imitation light in houses that influences our melatonin levels. 100 years ago we did not have a light source such as a television that bombards the brain with signals and light. Research has shown that watching television before going to bed can influence the sleep hormone melatonin drasticly. See the related link.