Eventually, everyone must sleep due to our

Natural cycles of activity that bodies must go through are called

The _____ is the internal clock that tells people when to wake up and when to fall asleep.

Which of the following parts of the body controls the sleep-wake cycle?

An example of a biological rhythm is

When a person is slightly sleep deprived, _____ tasks will suffer less than _____ tasks.

The _____ theory of sleep says that sleep is a product of evolution.

Carmen stayed up all night studying, getting only about two hours of sleep total. While she was able to finish her exam, she was unable to focus, and much of what she had studied the night before seemed to be forgotten. Carmen's inability to remember and to stay focused during her exam is most likely due to

In studies in which volunteers spend several days without access to information about day or night, their sleep–wake cycles