General Information

SAD Symptoms

In most cases, seasonal affective disorder symptoms appear during late fall or early winter and go away during the sunnier days of spring and summer.  Symptoms may start out mild and become more severe as the season progresses.

Fall and winter seasonal affective disorder (winter depression)
Winter-onset seasonal affective disorder symptoms include:
  • Hopelessness
  • Anxiety
  • Loss of energy
  • Heavy, "leaden" feeling
  • Social withdrawal
  • Oversleeping
  • Loss of interest in activities you once enjoyed
  • Appetite changes, especially a craving for foods high in carbohydrates
  • Weight gain
  • Difficulty concentrating

What About Blue Light?
Fall and winter seasonal affective disorder (winter depression)

There are many claims for blue light in consumer light products.  Most of the small light box units currently on the market provide far less than the recommended amount of light.  And they all emit mostly blue light.  A great many eye doctors, as well as most of the top light therapy experts believe that blue light could be harmful to the retina.  Just as a constant dose of UV can eventually lead to skin cancer, a constant large dose of blue light may lead to macular degeneration.   For this reason, most ophthalmologists who perform cataract surgery recommend that their patients implant a blue light blocking lens.  So, until blue light is proven completely safe, CLA companies advise consumers to continue using white light emitting light boxes and Visors.   

White light Visors and light boxes have been successfully used for over 25 years without any serious adverse effects.  These units have also been successfully used in several hundred clinical trials under the strictest safety protocols.

Please consult your own eye doctor if you have additional concerns.

What The Experts Say

Dr. Norman Rosenthal is a leading expert and original researcher in the field of light therapy.  He is the author of "Winter Blues."   In his 2005 revision of Winter Blues Dr. Rosenthal says "The bottom-line answer is, at this time stay with conventional white-light fixtures. We have decades of experience indicating that these are effective and safe. As of the writing of this book, there is not one published study on the effectiveness of blue light for treating SAD. Nor is there the long track record of safety. On the contrary, there is long-standing concern about potential toxicity of blue light to the eyes."


Leading International Research

The Society for Light Treatment and Biological Rhythms is an international organization of researchers and clinicians involved in the field of light therapy.  It's members are dedicated to research and clinical applications of light therapy and biological rhythms.

The Society states  "Early research used special "full-spectrum" bulbs producing light similar in color composition to outdoor daylight, but more recent devices have used ordinary fluorescent bulbs (cool white, warm white, and tri phosphor types) with similar results. (Since full-spectrum bulbs are designed to include ultraviolet light, which might contribute to cataract formation and skin problems, it is best to avoid such light at high intensity unless it has been carefully filtered for UV.) What appears to be critical is that the level of light produced match that of visible light outdoors shortly after sunrise or before sunset. Light intensity is critical for adequate therapy. Systems deliver varying amounts of light, which should be specified in detail by the manufacturer, with information provided as to how far away the patient should sit in order to receive the rated intensity."

Concerns over the possible hazards of blue light, which are near the UV portion of the light spectrum prompted the SLTBR to hold a special "Symposium on Safety Issues in the Use of Blue Light" at their 2005 Annual Meeting held in the Netherlands.

Cautionary Statements From The Literature

The following are quotes from medical journals and scholastic publications.

". . . continuous exposure to blue light is potentially dangerous to vision." Koide R, Ueda TN, Dawson WW, Hope GM, Ellis A, Somuelson D, Ueda T, Iwabuchi S, Fukuda S, Matsuishi M, Yasuhara H, Ozawa T, Armstrong D. Nippon. Retinal hazard from blue light emitting diode. Ganka Gakkai Zasshi. 2001 Oct;105(10):687-95.

". . . high levels of exposure to blue or visible light may cause ocular damage, especially later in life, and may be related to the development of age-related macular degeneration." Taylor HR, West S, Munoz B, Rosenthal FS, Bressler SB, and Bressler NM. The Long Term Effects of Visible Light on the Eye. Archives of Ophthalmology 1992; 110:99-104.

"I think chronic blue light is probably damaging." Joshua Dunaief, MD, in Bethke W. Should We Block The Blue. Review of Ophthalmology Oct 15 2003; 10(10).

"The high-energy segment of the visible region (400-500 nm) is enormously more hazardous than the low energy portion (from 500-700 nm)." Young RW. Solar Radiation and Age Related Macular Degeneration. Survey of Ophthalmology 1988; 32(4): 252-269.

"Visible light of short wavelength (blue light) may cause a photochemical injury to the retina, called photoretinitis or blue-light hazard." Okuno T, Saito H, Ojima Evaluation of blue-light hazards from various light sources. J. Dev Ophthalmol. 2002;35:104-12.

"[The] Action spectrum for blue-light induced [retinal] damage shows a maximum at 400 nm and 450 nm." Bartlett H, Eperjesi F. A randomized controlled trial investigating the effect of nutritional supplementation on visual function in normal, and age-related macular disease affected eyes: design and methodology. Nutrition Journal 2003, 2:12.

". . . blue light induces apoptosis in human fetal RPE cells." E.M. Gasyna, K.A. Rezaei, W.F. Mieler, and K.A. Rezai. Blue light induces apoptosis in human fetal retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 2005 46: E-Abstract 248.

"The effectiveness of light in inducing photo damage to the retina increases with decreasing wavelength from 500 to 400 nm." Andley UP,? L.T. Chylack Jr LT. Recent Studies on Photo damage to the Eye with Special Reference to Clinical and Therapeutic Procedures. Photodermatology Photoimmunology and Photomedicine 1990; 7:98-105.

"The photoreceptors in the retina . . . are susceptible to damage by light, particularly blue light. The damage can lead to cell death and diseases." Shaban H, Richter C. A2E and blue light in the retina: the paradigm of age-related macular degeneration. Biol Chem 2002 Mar-Apr;383(3-4):537-45.

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