The study is meant to determine which stages of sleep are safe from the unknown threat's attacks. The current hypothesis is that REM sleep is the only stage in which one can be assaulted with a nightmare that may result in death. However, previous studies have not revealed anything substantial. Further research has unveiled a potential cause: light.

[ Again, it sounds like Ratio is reciting this from memory, like he's said this a dozen times before. Most likely, anyone who's volunteered to participate has asked a similar question. ]