This article discusses a study published in the journal Lancet about the sleep patterns of astronauts in space. Since I don't have access to the Lancet article, I don't have all of the details. The article however states that the astronauts are scheduled to get 8.5 hours per day of sleep. On average, they managed to sleep about 6 hours. And 78% of them used sleeping pills about half of the time.
The article goes on to quote someone from NASA who states that the study demonstrates valuable insights into sleep deprivation experienced by astronauts in space. However, I'm not sure it does, but I am basing this on the article, not the actual study. The article doesn't give me any insight, only leads to more questions. Why are astronauts expected to sleep 8.5 hours per night? Who came up with that number? How was sleep measured in the astronauts? Subjective or objective information? For the astronauts that did not sleep the full 8.5 hours, were they sleepy in the daytime? Did they actually exhibit any signs of sleep deprivation? Why did the astronauts take sleep aids? Was it because they were told they needed to sleep 8.5 hours, but most realized they would not be able to do that because the amount of sleep they actually need is less?