Complex sentence: Experiments have shown that light entrainment, by which periods of behavioral activity or inactivity (sleep) are synchronized with the light-dark cycle, is not as effective in melanopsin knockout mice, while mice lacking rods and cones still exhibit circadian entrainment and pupillary reflex.
Split into simpler sentences: Experiments have shown that light entrainment, by which periods of behavioral activity or inactivity (sleep) are synchronized with the light-dark cycle, is not as effective in melanopsin knockout mice. By contrast, mice lacking rods and cones still exhibit circadian entrainment and pupillary reflex.