According to the American Academy of Sleep Medicine and Sleep Research Society, which of the following statements is true about an individual's sleep?
A. Family and social obligations predominantly lead to long hours of sleep in an individual's life.
B. Usually five hours of sleep a day is necessary for the optimal performance of an individual.
C. Chronic sleep deprivation may contribute to cardiovascular disease and a shortened life span.
D. The level of stress is independent of the quality or amount of sleep.