The four sentences (labelled 1, 2, 3 and 4) given below, when properly sequenced, would yield a coherent paragraph. Decide on the proper sequencing of the order of the sentences and key in the sequence of the four numbers as your answer.
1. Disrupt that flushing, and the residue that should have been swept out — including the protein fragments associated with Alzheimer's — instead accumulates between neurons.
2. For decades, sleep was treated as little more than a passive idling of the brain, useful for rest but otherwise uninteresting to those studying cognition.
3. This re-framing has quietly turned the most basic of biological habits into one of the most consequential interventions we know.
4. That assumption began to crack in the 1990s, when researchers showed that the brain's clearance of metabolic waste depends on a flushing system that runs almost exclusively when we are asleep.
1.Disrupt that flushing, and the residue that should have been swept out — including the protein fragments associated with Alzheimer's — instead accumulates between neurons.
2.For decades, sleep was treated as little more than a passive idling of the brain, useful for rest but otherwise uninteresting to those studying cognition.
3.This re-framing has quietly turned the most basic of biological habits into one of the most consequential interventions we know.
4.That assumption began to crack in the 1990s, when researchers showed that the brain's clearance of metabolic waste depends on a flushing system that runs almost exclusively when we are asleep.