www.journalsleep.org

Anchor text: An American Academy of Sleep Medicine Review: ''Circadian Rhythm Sleep Disorders: Part I, Basic Principles, Shift Work and Jet Lag Disorders.'' PDF, 24 pages. November 2007.

Wikipedia: Circadian rhythm sleep disorder

http://www.journalsleep.org/Articles/301108.pdf

Anchor text: An American Academy of Sleep Medicine Review: ''Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep–Wake Rhythm.'' PDF, 18 pages. November 2007.

Wikipedia: Circadian rhythm sleep disorder

http://www.journalsleep.org/ViewAbstract.aspx?pid=27091

Anchor text: Catathrenia (Nocturnal Groaning): What is It? (PDF available)

Wikipedia: Catathrenia

http://www.journalsleep.org/articles/110604.pdf

Wikipedia: Divergent thinking

http://www.journalsleep.org/Articles/281210.pdf

Wikipedia: Central sleep apnea