Circadian Rhythm (Wikipedia)
This extensive dictionary definition from the most popular on-line encyclopedia gives those with little knowledge about circadian rhythms an overview of the topic.

Circadian Rhythms (All Science Den)
This site discusses the topic of circadian rhythms in relation to cells and DNA in invertebrates and mammals.

Circadian Rhythms (Kimball's textbook)
This page correponds to the chapter on circadian rhythms in John W. Kimball's textbook Biology (6th Edition, Wm. C. Brown, 1994).

The Brain, Circadian Rhythms, and Clock Genes
This article by Dr. Michael Hastings includes diagrams and explanations of circadian clock molecules in flies and mammals.

Sleepless at Stanford
This article by Dr. William Dement discusses the need for adequate sleep and its connection with the biological clock.

Time Matters: Biological Clockworks
This section of the Howard Hughes Medical Institute's Biointeractive site details early circadian experiments dealing with plants and proceeds to current knowledge on circadian rhythms.

Biological Clocks: Lecture Series · Video
This page, also a part of Howard Hughes Medical Institute's Biointeractive site, contains links to video lectures on biological clocks by Dr. Joseph S. Takahashi and Dr. Michael Rosbash.

Clocks and Rhythms: Interviews · Video
This page contains links to numerous videos of interviews with biological rhythm researchers who attended the 72nd Cold Spring Harbor Symposium on Quantitative Biology in 2007.

Biological Clocks Program (Texas A&M University)

Biological Clocks Program (University of Houston)

Center for Chronobiology (University of Surrey)

Center for Human Sleep Research (Stanford University)

Center for Sleep & Circadian Biology (Northwestern U.)

Circadian Research Center (Uniformed Services Univ.)

Sleep and Circadian Group (Woolcock IMR, Australia)

Swiss Center for Chronobiology (University of Basel)

Circadian Lighting Association

European Biological Rhythms Society

European Society for Chronobiology

International Society for Chronobiology

Japanese Society for Chronobiology

Society for Light Treatment and Biological Rhythms

Society for Research on Biological Rhythms

Chronobiology International (Taylor & Francis)

Biological Rhythm Research (Taylor & Francis)

Journal of Biological Rhythms (Sage Publications)

Journal of Circadian Rhythms (BioMed Central)

Sleep and Biological Rhythms (Blackwell Publishing)

Circadian Technologies Inc.
This site is the homepage for Circadian Technologies Inc., a research and consulting firm that assists managers of shift work operations.

Shiftwork Solutions LLC
This is the homepage for Shiftwork Solutions LLC, a company that provides assistance to shift-workers to help them manage their workload fluctuations with the goal of lowering costs and improving productivity.

Jet Lag
This European site describes the causes of jet lag and provides several options for preventing it.

Seasonal Affective Disorder
This page from the Howard Hughes Medical Institute's Biointeractive site provides a description of Seasonal Affective Disorder.

Bipolar Disorder
This article by Dr. Ellen Leibenluft discusses mood and sleep issues in patients with rapid-cycling bipolar disorder.

Sleep Network and Sleep Disorders Guide
These two sites are packed with information about sleep disorders and their treatment.

Sleep and Circadian Rhythms
This health article from the Medical College of Wisconsin talks about sleep problems resulting from a disruption in one's circadian rhythms.

Sleeplessness and Circadian Rhythm Disorder
This article from eMedicine indicates that behavioral modification is helpful in patients with irregular sleep-wake cycles.

Circadian Biology and Clinical Medicine · Video
This video is a lecture by Dr. Charles Czeisler (Harvard Medical School) on "Application of Sleep Science and Circadian Biology to Clinical Medicine". (Running Time: 01:06:42)

Carl Johnson's Laboratory
The web site of Dr. Carl Johnson at Vanderbilt University (Cellular, molecular and evolutionary analyses of biological clocks).

Steve Kay's Laboratory
The web site of Dr. Steve Kay at the Scripps Research Institute (Genetics and genomics of circadian clocks).

Andrew Millar's Laboratory
The web site of Dr. Andrew Millar at the University of Warwick (Biological clocks in plants).

Choogon Lee's Laboratory
The web site of Dr. Choogon Lee at Florida State University (Molecular mechanism of mammalian circadian rhythms).

Chris Colwell's Laboratory
The web site of Dr. Christopher Colwell at the University of California, Los Angeles (Molecular, cellular, and systems-level mechanisms of circadian-rhythm generation).

Martha Gillette's Laboratory
The web site of Dr. Martha Gillette at the University of Illinois, Urbana-Champaign (Neuroscience of circadian rhythms).

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