Research on sleep patterns indicates that:

a. the elderly and newborns have very similar sleep patterns.
b. different sleep patterns reflect significant personality differences.
c. the duration and pattern of sleep among fraternal twins is strikingly similar.
d. everyone needs a minimum of 6 1/2 hours of sleep per night to function well.
e. sleep patterns may be genetically influenced.

Answer: e. sleep patterns may be genetically influenced.