Bedtime reading (3.8, 3.9) Is there a difference between reading an ebook and a printed book before going to bed? Researchers randomly assigned 12 young adults to read either an electronic book or a printed book for the same amount of time. They found that those who read the ebook had decreased sleepiness, reduced REM sleep, and a smaller increase in blood levels of melatonin, the hormone that regulates the sleep–wake cycle. Suppose you want to repeat this research with high-school-aged subjects, and you have 50 volunteers ready to participate
