Final answer:
Humans, on average, spend about one-third of their life sleeping, which equates to roughly 25 years given the average lifespan in the U.S.
Step-by-step explanation:
On average, humans spend approximately one-third of their lives sleeping. Given that the typical life expectancy in the U.S. ranges between 73 and 79 years, this could translate to about 25 years of sleep throughout a lifetime. The amount of sleep needed varies from person to person and decreases with age, with infants needing up to 16 hours of sleep a day and seniors often getting less than 7 hours. While some animals require little sleep without adverse effects, humans need sleep to function properly, and lengthy sleep deprivation can be harmful or even fatal, as shown in studies with rats. Understanding sleep's essential role in health and development is crucial, whether studying brain function, hormone regulation, or the theories explaining the need for sleep and dreaming.