Studies have shown that tired children have trouble learning because neurons become incapable of forming new synaptic connections that are necessary to encode memory.

The problem is that the school day starts too early. Awakened at dawn, teenage brains are still releasing melatonin, which makes them sleepy. Several years ago, Edina, Minnesota, changed its high school start from 7:25 a.m. to 8:30 a.m. The SAT scores for a random sample of students taken before the change and a random sample of SAT scores after the change were recorded. Can we infer from the data that SAT scores increased after the change in the school start time?