As you've discovered there are a lot of expensive products on the market making various claims. Technical lighting terms are mixed with marketing terms; current technology gets confused with older technology. Some products seem to be marketed to everyone who feels less energetic in the winter months.
Though our services do not include medical advice, in the course of preparing this case I have come across much information that may be of interest to you and am including some referrals to it for your own research. SAD is a serious disorder that is sometimes successfully treated with phototherapy, also called bright light therapy. Many insurance companies are now covering the cost of this treatment and it is necessary to check with your own insurer to determine if you have coverage and what conditions may apply. They may also have a list of products they will cover. SAD is not a condition for self-diagnosis or treatment and a doctor's supervision should be sought regardless of whether you pursue insurance coverage or not. Because our eyesight is precious before using bright light therapy you should check with your opthamologist as well. Cataracts and macular degeneration are both concerns related to the ultraviolet (UV) light from the sun. The goal with phototherapy is to get light into the eye, though not by looking directly at the source. Just as sun exposure must be limited when taking photosensitive medications, phototherapy may require the same. Consult your doctor. As with most illnesses the placebo affect generally causes about 20% of the population to respond positively in those using one and the same is true with phototherapy. For light therapy to show medically measurable improvement generally takes about three weeks. The Circadian Lighting Association requires its members to offer a 30 day, no questions asked, refund policy to allow time for customers to determine if the product is useful for them. While some users have a neutral response, a small number have found they suffer ill effects from the lights, usually anxiety, headaches, or nausea from the light.
The main device for treating SAD on the market is the light box. A light visor is also available as a battery operated portable method. Another device, the Dawn Simulator, is commonly seen alongside these products, but it is generally not used to treat SAD. It is a way to help those who have a hard time getting up in the dark wake-up. It consists of an electronic timer and dimmer switch, which gradually increase the light level over a time period, usually 30-45 minutes. Some products include the lamp while others do not. The number, intensity, and color quality of the lamps vary. Dawn simulators may or may not have therapeutic value for those afflicted with SAD. Because they do not involve bright light entering the eye they are of less concern medically.
The terminology used in advertising SAD products is a mix of correct technical lighting terms and less precise "marketing" terms. In spite of all kinds of advertising referring to the color of the light as important, existing, medically accepted studies used by the National Institute of Mental Health only show a benefit realized based on the intensity of light. Please read the enclosed attachment from the Lighting Design Lab in Seattle WA regarding "full spectrum" light sources. There are several organizations you may also be interested in contacting about SAD and its treatment, which I have listed at the end of this letter.
If you have decided to purchase and use a light box it may be helpful to understand some basic lighting terms and descriptions. The two most common descriptions of light I find involved with light boxes is "10,000 Lux" and "full spectrum light". Artificial light is technically described in terms of the way objects appear in the light, described by CRI (color rendering index) and CT (color temperature), source, such as incandescent or fluorescent or LED (light emitting diodes), how much light the lamp emits and how much power, in watts, it uses.
The lumen is a technical term found in lamp manufacturer catalogs and calculations by lighting designers and others. The simple definition is the amount of light a lamp emits the higher the number the more light you get. How much usable light is on the surface of an object being viewed is measured in footcandles, defined as one lumen per square foot or lux, defined as one lumen per square meter. These quantities can be measured with a light meter. Light follows the inverse-square law: Illuminance at a point varies directly with the intensity, I, of a point source and inversely as the square of the distance, d, to the source. E = I / d2. Therefore, unless you are at the exact distance from the lamp the 10,00 lux in an advertisement is stated for (and many do not point this out) the lux that can enter your eye, which is what counts in treating SAD, will differ. You cannot find a "10,000 lux" lamp in a lighting catalog. Some companies clearly state at what distance their lamps measure 10,000 lux and it varies considerably. Think about where you want to use the lamp, generally 30-45 minutes in the morning is suggested- again, talk to your health care provider, not the salespeople, and how workable the size of the lamp will be.
Lumen depreciation factor refers to the light loss of a luminaire (fixture with lamp) with time due to the lamp filament deteriorating, discoloration on the interior of the bulb wall, dirt accumulation, and other factors. All lamps suffer this condition, some more quickly than others do. In lamps with short lives (700-100hours) such as incandescents it is not so important because by the time the bulb wall is blackening the lamp generally fails and is replace. With long-lived lamps (5-20,000 hours) like fluorescents, it makes a difference when a particular light level is required. Lamp catalogs will designate both initial lumens (the first 100 hours of use) and maintained lumens. Many advertisers like to boast about initial lumen numbers though it is the maintained lumens that are more important over the life of the lamp.
How people and objects appear under any given light is described by how accurately they appear compared to natural daylight. The human eye sees only a small part of the spectral wavelengths emitted by the sun; we do not see the ultraviolet (UV) which causes suntans or sunburns, or infrared (IR) wavelenths and much more. A full spectrum would include all the spectral emissions. Most of us perceive a difference in how colors look outside at midday to sunrise and sunset periods. We also see our clothes and skin tones somewhat differently under fluorescent, incandescent, or daylight. New fluorescent technology has greatly improved and can simulate daylight or incandescent light quite closely. Much of the literature I came across researching this case was comparing the "SAD lamps" against old fluorescent technology, when in fact many of the SAD lights on the market are using the same new technology lamps available from all the major lamp manufacturers.
There are two interrelated ways of describing appearance of illuminated objects, the color rendering index, CRI and color temperature in degrees Kelvin. The CRI is a scale of 0-100 and refers to how colors shift away from "natural"(midday sunlight) appearances. CRI cannot accurately be discussed without including color temperature, CT, measured in degrees Kelvin (K). The technical definitions are described in the enclosure from the Lighting Fundamentals Handbook. The higher a color temperature is the whiter and bluer the light appears. The sky at noon ( 5000+K) is a blue color. Both sunlight and a standard incandescent lamp (CT about 2700K) have CRI's of 100, yet a photograph of the same subject under each light source will not appear the same, the lamp lit object will have a warm yellowish cast while the skylit object is cooler and bluer. This points out the necessity that the CT must be the same or nearly so to compare lamps and their CRI 's and the appearance of objects being lit. Lamps in manufacturer's catalogs state CRI and CT. Much SAD literature does not, preferring terms such as "natural, broad, wide or full spectrum". A lamp manufacturers catalog will have "high color rendering" lamps, but not "full spectrum" lamps. I have found "full spectrum" lamps described in sales literature and by their representatives as having CRI's from 82-100 and CT's from 4100-7500K. Though they are called "full spectrum" they are not all the same lamps. Some of the "full spectrum" lamps have added UV light to make them more like the sun, then advertise their special UV filtering lenses to protect you from the UV light!
We all experience colors in subtly different ways and it can affect our mood as well. It may energize us, relax us, increase our appetite, or agitate us. It can make our complexion appear healthy or sick. The choice of color from a lamp for SAD treatment is a personal one. Many people object to the poor color produced by the old cool-white fluorescent lamps (CRI62, CT 4100K), common in offices, schools, and other commercial spaces. In comparison they will often think things look much better and perceive that they feel better to under a "full spectrum lamp". They may "feel" equally as well with a good fluorescent lamp with a CRI of 85 and a CT of 4100, one of the lamps that is often replacing the old cool-whites. At least one company sells a SAD product that consists only of green light and claim a study by the University of California showed better results than a full spectrum lamp.
10,000 lux is the most commonly advertised quantity of light to treat SAD, with about a 30 minute exposure. Three to four hours at 2500 lux is also frequently mentioned and may be accomplished with less light positioned close to the user or the more powerful lights moved further away. Basically light brighter than 250 foot-candles has been shown to be effective treatment for some sufferers of SAD. For comparison, an average office space or classroom ranges between 50 and 100 foot-candles.
It is the light reaching your eye that counts in treating SAD, but staring into the light is not recommended. Generally they are shown to be in your peripheral vision and most have filters to reduce glare. Suggested activities while under the light include reading, eating, watching television, computer use and exercise. Since your position relative to the lamp affects how much light gets into your eye, the brighter light for a shorter time might not be as effective if you are moving about exercising, and you would need to avoid positions that would have you looking directly at the light. Some companies caution you to consult your doctor about how long to use their lights, some just suggest you start slowly and work up to 10,000 lux as you get used to the light. At least one company I talked to provides a chart correlating distance to lux.
The company that markets the green only lamp uses a much lower intensity than many others do, in a room with very little other light besides a television or computer screen. They argue that additional ambient light desensitizes the eye and that by reducing it, much less concentrated light is required to treat SAD, and it can be done more comfortably as well. Their product would not work in an office building with ambient lighting on, but may work in a private office where the other lights are turned off.
Lamps cost us money when we purchase and replace them, which is a lump sum, and every time we use them, which gets buried with everything else on your electric bill and often costs many times the cost of the lamp itself.
Incandescent technology is what most of us think of when we think of a light bulb. The filament is heated by electricity until it glows and the resulting light is what we use. The more power used and larger the filament, the brighter the light. A 100-watt lamp produces around 1500-1600 lumens. Unfortunately the light is really a by-product of the device which uses 90% of the energy to make heat and 10% for light making them large power consumers. Each lamp burns around 750 hours before the filament fails. Though inexpensive to purchase, the real expense is in operating them. The CRI of the standard incandescent is rated at 100 and the CT is 2700K. There are some "full spectrum" incandescent lamps on the market. They cost around 10 times as much as standard incandescents and some may last about twice as long. They have a coating on the lamp wall, which filters out much of the yellow light to make them appear "cooler" and more like daylight.
Fluorescent lamps have long been known as more efficient than incandescents and for that reason were popular with large users in commercial, institutional, and industrial settings. They last 10-20,000 hours and use much less power for the amount of light they generate. Historically they were all large, long lamps and required a ballast and special fixture to operate. The ballasts were electromagnetic and often emitted a buzzing noise and noticeable flickering light, which many people found objectionable. The color quality, as discussed above, left a lot to be desired as well. New lamps are smaller, and include compact fluorescent lamps (CFL) which screw into standard lamp sockets, as well as some that use only special fixture. Electronic ballasts eliminate both flicker and noise. Some of the SAD advertising does not acknowledge the new technology as available outside of their "special no flicker, no noise" product. When I could get a representative to quote CRI and CT, most products are in fact standard products. The extra high CRI lamps, those above 90, including "full spectrum", command premium prices and sacrifice some efficiency in light output as well. The compact fluorescent lamps are available in both magnetic or electronic ballasted models, with the same operating considerations of the full-size lamps. They also come in several colors, including high color rendering versions. "Full spectrum" lamps in both configurations are on the market at premium prices. The full size lamps generally have live's of 15-20,000 hours while the CFL's average 10,000 hours. Though the initial purchase price of lamp and ballast is higher than incandescent lamps they cost less when replacement costs and energy use over their life is included. As with any energy consuming appliance the longer a device is operated the more important the efficiency is. In treating SAD operating a light box for thirty minutes in close proximity would be more economical than using the same lamp at a greater distance for a period of several hours. If you decide to use lower intensity light it would be more economical to use fewer lamps in close proximity. A fluorescent system will be more economical to operate than an incandescent. Most units seem to use between 40 and 120 watts and utilize the larger cfl lamps.
Some other features often advertised are special grounding plugs and radiation shielding. Any unit you use should be UL listed which pertains to fire safety. The electronic ballasts do not generate the electromagnetic fields some people are concerned about (not that these fields have anything to do with SAD at all) and some of the advertised claims imply that their special electronic ballasts don't have this problem, but they are not unique in that. "Tighter European standards" is put forth by those who know Americans are, in general, intimidated by the "made in Europe" label as being of higher quality than "made in the USA." The ONLY "tighter standard" in the European market is ISO 9000 / 9002, which is an effort by the EEC to restrict American imports without violation of WTO accords. The "radiation shielding" usually consists of "special" lenses or some tape wrapped around the base of the lamps at the socket connection. As no details about how this worked or how much it helped was available this may have more to do with sales enticement than documented fact.
Other features of light boxes are for appearance or versatility and a matter of personal choice.
Some people looking for alternatives to the expensive, ready-made products have built their own. If you are comfortable with basic electrical skills, wiring a ballast is not particularly complex. Purchasing a 2' X 2', surface mounted, lensed troffer with as many lamp sockets as available for biax lamps. Basic white finish is suggested. If you want to pursue this option contact me regarding fixture sources. The lamps you use should be at least CRI of 82 and CT of 4100, after that it's your preference. Be sure to get a compatible ballast, cord and plug. A rough estimate places the cost around $130. Compare pricing the components and your labor versus the purchase price of a ready made unit. If you are seeking insurance reimbursement I suspect this is not an option so be sure to check. The 30-day trials offered by many companies seem like a good way to try before you buy.
There are many articles about SAD and its treatment, and ongoing research. One source often referred to is Dr. Norman Rosenthal, M.D. who wrote "Winter Blues: Seasonal Affective Disorder and How to Overcome It" in 1993. Another name you will see a lot is Dr. John Ott, a photographer who began investigating the effect of light on his subjects including people and plants. At the time he was writing his early work all fluorescents were operated on magnetic ballasts and of the poor color rendering type, much of his work has been criticized as unscientific, but several companies cite his support of "full-spectrum" lighting in their advertising.
I hope this information helps you locate a product that will be useful to you. Getting outdoors daily, even on overcast days does expose you to much higher amounts of light than any typical indoor condition. Check out the enclosures and resources listed for more detailed information and if you have further energy-related questions please contact the Energy Ideas Clearinghouse at (800) 872-3568.