1. In general, as the cycle of sleep recurs through the night, it tneds to contain
A. more stage 4 and less REM
B. more stage 4 and more REM
C. less stage 4 and less REM
D. less stage 4 and more REM
2. If the human eye was not responsive to differences in the wavelength of light, we would not be able to perceive differences in
A. brightness
B. saturation
C. color
D. purity