IMAGES PROVIDED BY:
1) Eric Anthony Johnson / 81a
2) Paul Bradbury / OJO Images
3) Lilli Day / Photodisc
4) Jacob Hutchings / Digital Light Source
5) Jose Luis Pelaez Inc / Blend
6) Charlie Abad /Photononstop, inset: Andrew Syred/Photo Researchers, Inc.
7) Siri Stafford / Stone
8) Radius Images
9) Slivinski Photo / Photographer's Choice
10) Markus Bernhard / Taxi
11) Davies and Starr / Digital Vision and Thinkstock
12) Tony Cordoza / Photographer's Choice
13) Thinkstock
14) Vilhjalmur Ingi Vilhjalmsson / Flickr
15) PASIEKA / Science Photo Library
16) Adam Gault / OJO Images
17) Nick Vedros & Assoc. / Photographer's Choice
18) Elea Dumas / Brand X Pictures
19) David Elliott / Iconica
20) Blake Sinclair / Workbook Stock
REFERENCES:
Qanta Ahmed, MD, sleep specialist at the Winthrop-University Hospital Sleep Disorders Center in Mineola, N.Y.
National Sleep Foundation: "Jet Lag and Sleep," "Cognitive Behavioral Therapy for Insomnia," "Can't Sleep? What to Know About Insomnia," "The Sleep Environment."American Academy of Sleep Medicine: "Sleep Hygiene – The Healthy Habits of Good Sleep."
Tworoger, S. Sleep, November 2003; vol 26(7): pp 830-6.
Sleepbetter.org: "17 Healthful Sleep Tips."
Paul Zolty, MD, Sleep specialist Georgia Lung Association.
National Institutes of Health: "Facts About Insomnia."