New evidence of age-related decline in the brain's master circadian clock The SCN keeps the system of multiple distributed circadian oscillators in synchrony, but disruptions in the SCN lead to disrupted sleep, as well as dysfunction in memory, the cardiovascular system, and the body's immune response and metabolism. ... the difference between the highest levels of activity during the daytime and the lowest levels of activity during the nighttime is much smaller in the middle-aged mice." in Public bookmarkswith healthmemoryrhythmsleepsystem