Frequently Asked Questions About SAD (Seasonal Affective Disorder)
1. What is light therapy?
Light therapy involves daily, scheduled exposure to intense levels of artificial light in order to regulate seasonal mood swings, improve sleeping patterns, and produce a general sense of well-being. According to medical researchers, the fluorescent light box is the preferred device for light therapy, with a recommended starting dose of 10,000 lux for 30 minutes per day. (Lux is the unit of measuring the illumination intensity of light.)
2. What is light therapy used for?
Light therapy was originally tested and developed by medical experts in the early 1980’s for treating Seasonal Affective Disorder (SAD) - a type of recurrent, major mood disorder regularly experienced by some people during the fall and winter months. Those with SAD are often quite incapacitated by depressive episodes and require medical treatment. During the spring and summer, however, their symptoms usually disappear.
More recently, researchers have explored the benefits of using bright light therapy on people with “subsyndromal” SAD - commonly known as the “Winter Blues,” and studies indicate a good response rate. Other conditions for which light therapy looks promising include non-seasonal mood disorders, bulimia nervosa, panic disorder and premenstrual syndrome (PMS). Doctors who use lights with pregnant women to avoid pre- and post-natal blues have reported encouraging results. Other studies show light therapy useful in certain disorders of the circadian system (i.e., the internal biological clock) including circadian sleep phase disorders, shift work, and jet lag.
3. What is the difference between Seasonal Affective Disorder (SAD) and the Winter Blues?
Many people, especially in northern latitudes where winter hours of daylight are fewer, complain of feeling down, having less energy, putting on weight and having a hard time getting up in the morning. This is what we refer to as “having the Winter Blues.”
Although there are variances among individuals, most people with SAD experience all of these symptoms, but to a much greater degree. They are often despondent and fatigued, and want to withdraw from the world. They may increase their sleep by as much as four or more hours per day, or have greatly increased appetites - sometimes accompanied by extreme cravings for sweet and starchy foods. Women frequently report worsening of premenstrual symptoms. In short, people with SAD suffer in the extreme the kinds of changes most of us experience in wintertime, and require medical treatment - either light therapy or antidepressants.
4. How prevalent is SAD?
According to a recent report published by the Canadian Consensus Group for the Treatment of Seasonal Affective Disorder (please see reference section), SAD is conservatively estimated to occur in up to 3% of the Canadian population, and 1% of the US. For recent population figures, that means as many as 3 million Americans and 900,000 Canadians suffer from SAD.
The number of people, however, who experience the Winter Blues is much greater. A recent estimate suggests eleven times as many people suffer from the Winter Blues as are diagnosed with SAD, and some studies indicate as much as 25% of the Canadian population experience some degree of winter doldrums. Women are at least twice as likely to have SAD as men.
5. How do I know if I could benefit from using a bright light system?
You could benefit from using a bright light system if you experience any combination of the following symptoms during the winter months: feeling down, moodiness, loss of energy, fatigue, lethargy, difficulty getting up in the morning, excessive sleeping, loss of sex drive, social withdrawal, cravings for carbohydrates, weight gain. You may also benefit from using a light if you are a shift worker, or frequent flyer.
If you suspect you have SAD, consult your physician for treatment guidelines. Individuals respond differently to various treatments and need to be supervised by a medical professional.
6. Have bright light systems been proven to work?
Yes. Since the first controlled light therapy study in 1984, there have been more than 60 controlled studies published by researchers around the world. Experts are now confident that bright lights work for the majority of people with SAD. (Response rates of 60% to 90% have been shown). Accordingly, a report called the Canadian Consensus Guidelines for the Treatment of Seasonal Affective Disorder (published in 1999 and partially funded by Pfizer) recommends light therapy as an effective first-line treatment for SAD.
Several controlled studies have also found light therapy beneficial for those with subsyndromal SAD (Winter Blues), and its effects on human body rhythms, independent of any effects on mood, are recognized (e.g., for shift work or jet lag). Although medical researchers are hesitant to make treatment recommendations without further research in these areas, the Canadian Consensus Group considers existing studies “encouraging.”
7. How do bright lights work?
The exact cause of Seasonal Affective Disorder has yet to be scientifically proven, and so the mechanism by which bright lights work remains hypothetical. However, light therapy has been statistically proven effective in the treatment of SAD, which puts the role that daylight plays in regulating our daily body rhythms in the forefront of research.
Two main hypotheses are postulated:
Bright lights work because they reset the daily body clock (i.e., circadian rhythms) which, for people with SAD, tends to get out of balance during the winter;
or Bright lights work because they help increase the level of the serotonin (a neurotransmitter that positively affects moods) which would otherwise decrease in the fall and winter.
8. How long does it take to experience the benefits of using bright light therapy?
Response to light therapy is usually very quick, and most people will notice a marked improvement within one week. Most people similarly experience a rapid recurrence of symptoms if they stop using their bright light system.
Longer trials have also shown increasing response to light therapy after two weeks, with still more incremental improvements after three or four weeks. Therefore, it is recommended that you continue to use a bright light system for at least a month before concluding it will not help you.
9. Could I get the same benefits by increasing the lighting in my home and office?
If you are particularly light-sensitive, you may feel more uplifted with increased exposure to normal room lighting. However, research studies show that much higher light intensities (at least 2,000 lux) are required in order to produce the desired therapeutic effects, and it is just not possible using regular fixtures to get ambient lighting above 600 lux.
Note also that medical experts caution against constructing your own bright light apparatus because of possible electrical hazards, as well as the difficulty in determining adequate light intensity and ensuring ultraviolet (UV) light rays are properly filtered.
10. What about spending more time outdoors -- would that work?
You should be able to satisfy your need for light by spending more time outdoors during the fall and winter days, as long as you can be outdoors regularly and for extended periods of time if conditions are cloudy. Most people find that difficult to do if they work indoors and have to keep an office schedule. The use of a 10,000 lux bright light system is therefore the most convenient way to get the light you need.
11. Are there any side-effects from using bright light systems?
Using a properly constructed bright light system as recommended is considered very safe, and few people have to desist use because of side effects. A few temporary side effects, such as slight nausea, tend to pass quickly as you get used to the high intensity of light. The majority of side effects, such as headache, eye strain, agitation, insomnia or difficulty getting to sleep, are caused by overdoing light therapy sessions. (In this case, it is possible to get “too much of a good thing.”) Such symptoms usually disappear when you decrease the “dosage” of light to your optimal level (usually in the 20 to 30 minute range).
If you have clinically diagnosed SAD, you may experience other personal variances which should be assessed and monitored by your doctor.
12. What if I’m on antidepressants, can I use lights?
That depends. If your depressive episodes are not seasonally triggered, it is unlikely that a bright light system alone will alleviate your symptoms. However, a bright light might help uplift your mood, and, if your doctor recommends it, can be used in conjunction with your medication.
For treating SAD, bright light systems are recommended as the first-line, “gold standard” treatment. Many people enjoy remission of symptoms simply by using light therapy. Others may not respond at all, though they are in the minority. Still others may be prescribed anti-depressants in conjunction with light treatment. Because individual needs can vary widely, your treatment regime should be supervised by your doctor.
13. When is the use of a bright light system not recommended?
There are no absolute contraindications to light therapy. However, if you have any eye problems (e.g., glaucoma, cataracts, retinal detachment, retinopathy) or have predisposing factors for eye complications (e.g., diabetes, lupus), or if you are taking medications that have photosensitizing effects in humans (e.g., lithium, melatonin), you should not use a bright light system without first consulting your physician. Your doctor will need to assess your individual risk-benefit ratio of using bright lights.
14. Are bright lights medically approved?
At this point in time, bright light systems have not been approved as “medical devices” by government regulatory agencies in either the US or Canada. However, in so far as researchers have proven the effectiveness of light therapy and recommend it as a first-line treatment for SAD, bright light systems have gained the approval of the respected medical community. It will take time for regulatory bodies to catch up with research.
15. Are lights covered under my medical insurance, and do I require a prescription?
Many private insurance companies recognize the benefits of light therapy and its cost advantages over antidepressant medication, and will cover the purchase of a light system with a prescription from your doctor. You should phone your insurance company before making the purchase to discuss coverage and specific documentation requirements.
Bright lights are not approved for reimbursement under Medicare, and are available widely for purchase without a prescription.
16. What is the correct way to use SAD Light products for therapy sessions?
For light therapy sessions, you would use your Day-Light each morning for 20-30 minutes during the fall and winter months. To receive 10,000 lux, you would need to sit approximately 12 to 15 inches from the light. During the session, you should NOT look directly into the light, but read, eat breakfast or do some paperwork.
17. Why do I need 10,000 lux?
10,000 lux for 30 minutes in the morning is what the experts recommend as a starting dosage for light therapy. Individuals may need to adjust the duration up or down from the 30 minute starting time, or use the light at a different time of day, depending on personal response to treatment. You can also get the appropriate dosage of light using a 2,500 lux system for two hours per day, but obviously this is far less convenient for most people. Our Day-Light provides 10,000 lux at 12 inches.
18. Do these lights cause tanning?
SAD Lights do not cause tanning because the ultraviolet (UV) rays that cause tanning are filtered out. Medical experts caution that exposure to unfiltered bright lights for extended periods of time may eventually cause ocular damage. It is the intensity of light that provides the therapeutic advantage, not the light spectrum. Be wary of “full spectrum” lights unless they are UV filtered.
References & Further Reading
1. Canadian Consensus Guidelines for the Treatment of Seasonal Affective Disorder
Lam, Raymond W. and Levitt, Anthony J., Editors, Clinical and Academic Publishing, Canada, 1999
2. Winter Blues: Seasonal Affective Disorder: What It Is And How To Overcome It
Rosenthal, Norman E, Guilford Press, New York, 1998
3. Seasonal Affective Disorder and Beyond: Light Treatment for SAD and Non-SAD Conditions
Lam, Raymond W., Editor, American Psychiatric Press, Washington DC, 1998
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