Our tendency to feel wakeful and sleepy on a 24-hour basis depends mainly on

A) a cycle generated by a mechanism in the brain.
B) our perception of environmental stimuli such as heat and light.
C) a cycle generated by hormone-producing organs such as the adrenal gland.
D) wear and tear on the muscles followed by a period of repair.

Brain Mechanism

Refers to the underlying biological structure and function involved in the processing of neural information in the brain.

Hormone-Producing Organs

Organs in the endocrine system that secrete hormones into the bloodstream to regulate various bodily processes, including the pancreas, thyroid, and adrenal glands.

Environmental Stimuli

External factors or conditions that can elicit responses from an organism or influence its behavior.