Let’s imagine that we had a hunch that lighting incense at midnight contributes to weight loss, and we wanted to test that hunch. How would we do that? We would recruit lots of overweight adults and (with their permission) randomly assign them into two groups. The first group would receive a wakeup call every night at midnight and would then light some incense. The second group would still receive a wakeup call (so that the sleep deprivation itself is not a difference between the groups) and w...