♪ i've been up all night ♪ i've been up all night well, as kids get ready to peri head back to the class -- kids love this team of year. there is new research on students, sleep and how they get ready for school. >> it turns out cramming for a test may be very counterproductive. i always loved pulling an all-nighter, didn't you? >> studying? >> yes. abc's medical contributor, dr. timothy johnson explains. >> reporter: school bells should not be competing with alarm clocks. a study in the journal "child development" finds evidence that burning the midnight oil to cram for tests is often t...