Bright light therapy is an important but definitely underutilized treatment in mental health. We want to recommend bright light therapy to our patients in an effective and safe manner. There are two issues in this regard— using an appropriate device and doing the therapy in the correct way.
First, let us look at how we can guide our patients in buying a proper device. How to correctly do bright light therapy is covered on a separate page (see Related Pages below).
Intensity of the light
1. We must make sure our patients understand that bright light therapy is not simply being in a brightly lit room. One cannot go to the local store and get a nice lamp. For bright light to be a treatment for seasonal affective disorder or other conditions, it has to be light of a particular intensity.
The intensity of light is measured in the units of “lux.” Ideally, the device for bright light therapy should provide light of 10,000 lux intensity. With such a device, a 30-minute session of light therapy every day is sufficient for most persons.
2. The relationship between intensity of light and the required duration of treatment:
If a lamp of slightly less intensity is used (e..g, 7,500 lux), the duration of daily light therapy would have to be increased to 45 or 60 minutes.
3. It is important that the lamp be at a certain distance from the person’s face.
It should be noted that the light intensity specified for the lamp (e.g., 10,000 lux) is at a particular distance as specified by the manufacturer. If the person using the lamp sits at a distance greater than that specified by the manufacturer, the intensity of the light received will be less. Only a few devices can provide 10,000 lux at 18 inches or more. Other devices require the person’s face to be only 12 inches from the device in order to receive the full 10,000 lux intensity of light.
What kind of light?
What about the different types of light that a device can provide or other gadgets that are advertised so often?
I suggest that we make it clear to the patient that bright white light is what is recommended.
Full-spectrum light? Some lamps claim to provide “full-spectrum light.” However, there is no known advantage to using these lamps.
Blue light? While blue light lamps have been promoted a lot recently, there is limited data on them. While blue light treatment was found to be more effective than placebo ((e.g., Glickman et al., 2006; Strong et al., 2009), I am unaware of any clinical trial comparing blue light to bright white light, which is the established type of light we use. So, at this time (as of November 2017) Simple and Practical Mental Health does not recommend the use of blue light for bright light therapy.
Other devices? Similarly, the efficacy of devices using LED technology, dawn simulators, visors (e.g., Rosenthal et al., 1993), etc is not established. At this time (as of November 2017) Simple and Practical Mental Health does not recommend their use for major depressive episodes with seasonal pattern.
I will continue to look into these alternative devices and will share with you any new conclusions that I may arrive at in the future. For now, it is probably best to stick with the tried-and-tested fluorescent white light as the primary treatment modality.
Ultraviolet light filter
It is extremely important that the device have a filter for ultraviolet (UV) light because UV light is harmful to the eyes and skin.
Size of the lamp
Having a larger lamp or light box is better because even if the person moves a little bit, s/he will still be within the zone in which light is being effectively delivered.
The light should come to the eyes at an angle in such a way that there is not an intense glare that makes the person want to look away.
For all the reasons discussed above, it is not a good idea to buy a light therapy lamp or light box except one manufactured by a well-known company that specializes in such products. Even with a reputable company, avoid the smaller devices or those with a lower intensity of light.
Another criterion that can help choose a bright light therapy device is whether that particular device has been shown to be efficacious in clinical trials.
Even though many “fancy” devices are available that make various claims, in my opinion, it is best to stick with devices that have a proven track record.
A systematic evaluation of bright light therapy devices
Specific bright light therapy devices/ lamps to recommend or not recommend
Bright light therapy: Instructions to patients
How exactly to use bright light therapy for bipolar depression
Seasonal Affective Disorder
Dr. Raymond Lam on Seasonal Affective Disorder-Part 1 (YouTube video)
Dr. Raymond Lam on Seasonal Affective Disorder-Part 2 (YouTube video)
Center for Environmental Therapeutics: Light Box Selection Criteria
Glickman G, Byrne B, Pineda C, Hauck WW, Brainard GC. Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs). Biol Psychiatry. 2006 Mar 15;59(6):502-7. PubMed PMID: 16165105.
Rosenthal NE, Moul DE, Hellekson CJ, Oren DA, Frank A, Brainard GC, Murray MG, Wehr TA. A multicenter study of the light visor for seasonal affective disorder: no difference in efficacy found between two different intensities. Neuropsychopharmacology. 1993 Feb;8(2):151-60. PubMed PMID: 8471127.
Strong RE, Marchant BK, Reimherr FW, Williams E, Soni P, Mestas R. Narrow-band blue-light treatment of seasonal affective disorder in adults and the influence of additional nonseasonal symptoms. Depress Anxiety. 2009;26(3):273-8. doi: 10.1002/da.20538. PubMed PMID: 19016463.
Waxler M, James RH, Brainard GC, Moul DE, Oren DA, Rosenthal NE. Retinopathy and bright light therapy. Am J Psychiatry. 1992 Nov;149(11):1610-1. PubMed PMID: 1415836.
Last edited October 30, 2017
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What is the scientific reason why LED sourced light would be different from fluorescent light in its therapeutic effect if the intensity is 10 000 lux (apart from this specific source not having been used in clinical trials)?