*tiredness. All of the people had MRI brain scans and did tests during the day. The people
in Group A said they felt less sleepy. They did the tests
の (quick) than the people in Group
B.
ウ
There were big differences between two groups. The researchers said people in Group
(い) have to get up early for school and work. They always want to sleep late, so they have
to fight their natural rhythm.