Your Friend Has Been Sleeping Six Hours Each Night and Is

Your friend has been sleeping six hours each night and is wondering if he is sleep-deprived. Which of the following statements is most accurate about your friend's sleep patterns?

A) Six hours per night is below average, but if your friend feels rested and productive then it might be normal for him.
B) Sleep deprivation is defined as fewer than six hours sleep per night, so your friend is close to a risky level.
C) Six hours per night is typical and sufficient for most young adults.
D) Each person is different and there is no such thing as a typical amount of sleep.