Passage Summary: In a sleep study, almost everyone felt better for two weeks and then went back to being awake all night in the third week, regardless of whether they took the real medicine or a sugar pill.

Reasoning: Both the group receiving a new drug and the group receiving a placebo experienced identical patterns of initial relief followed by a relapse in the third week.

Analysis: The paradox here is the synchronized timing of the improvement and the relapse across both groups. If the drug were the cause, the placebo group shouldn't have improved; if the placebo effect were the only factor, the sudden relapse in the third week for both groups remains a mystery. We need a piece of information that affected everyone at the institute simultaneously. Look for an answer that introduces an external variable, like a change in the institute's environment or the participants' awareness of the study's timeline, that explains why everyone’s sleep patterns shifted at the exact same time.