Columbia University Medical Center
Ranked #1 in Psychiatry
U.S. News & World Report
Ranked #1 in Research Funding
National Institutes of Health
NewYork-Presbyterian Hospital The University Hospital of Columbia and Cornell

Ask the Experts


I have heard that dawn simulators can achieve the same results as light therapy in the treatment of S.A.D. Is this true? If so, are there any specifications regarding the type of dawn simulator?

Answered by: Michael Terman

Several controlled clinical trials have shown that a slow, gradual rise in bedroom illumination in early morning toward the end of sleep can have an antidepressant effect similar to post-awakening bright light therapy. In winter, this dawn signal comes on while it is still dark outdoors. In setting up for dawn simulation, you should use a light source that delivers a wide field of diffuse illumination over the area of your pillow to make sure you receive the signal regardless of your sleeping posture. Avoid the commercialized "dawn alarm clocks" with attached lamps, which are too small and directional. Use a specialized dawn simulation control box to drive the lamp, which should rise to full room light intensity (about 300 lux). One commercially available control box is called the SunUp. Other suitable products are in the pipeline for winter 2007-2008. One useful lamp configuration is described at