Psychology: "Chapter 4: States of Consciousness"
Read the introduction to Chapter 4 and sections 4.1 through 4.4. After you read, you should be able to differentiate between consciousness, biological rhythms, and sleep, and be able to characterize the different stages of sleep.
Click https://cnx.org/contents/Sr8Ev5Og@7.2:zywvQOJS/Introduction link to open resource.