Circadian Sleep Disorders Association - - Support and providing information to those affected by circadian sleep disorders such as Delayed Sleep Phase Syndrome. Includes links, FAQs, message board and a mailing list.
Delayed Sleep Phase Syndrome - - Comprehensive site with symptoms, causes, treatments, and links to further information on DSPS and circadian rhythms.
Society for Light Treatment and Biological Rhythms - - A not-for-profit international organization founded in 1988 which aims to foster research, professional development and clinical applications in the fields of light therapy and biological rhythms.