You can directly support Crash Course at www.subbable.com/crashcourse Subscribe for as little as $0 to keep up with everything we're doing. Also, if you can afford to pay a little every month, it really helps us to continue producing great content. Why do we sleep? Well... that's a tricky question. More easily answered is the question,"How do we sleep?" In this episode of Crash Course Psychology, Hank discusses some of the ways our brain functions when sleeping and how it can malfunction as well. -- Table of Contents Four Stages of Sleep 02:38 Why We Dream 04:28 Information Processing 08:13 Physiological Function 08:31 Cognitive Development 08:52 Neural Activity Models 09:04 -- Want to find Crash Course elsewhere on the internet? Facebook - www.facebook.com/YouTubeCrashCourse Twitter - www.twitter.com/TheCrashCourse Tumblr - thecrashcourse.tumblr.com Support CrashCourse on Subbable: subbable.com/crashcourse