Beyond Medication: Bright Light Therapy for Depression

What Is Bright Light Therapy?

Bright light therapy involves exposure of the eyes to bright light for a specific duration of time on a daily basis. The person sits next to a light box or a lamp that emits a full-spectrum light. It is a safe, rapid, and effective way of treating depression, both the seasonal variety which commonly happens during winter and the non-seasonal ones (American Psychiatric Association, 2010; Morgan & Jorm, 2008). Bright light therapy is also beneficial for sleep disorders in people with sleep-wake cycle disturbance, especially in older adults (Sloane et al., 2008).

Seasonal Depression and Bright Light Therapy

If you are getting symptoms of depression every fall or winter and they usually go away around springtime, then it is likely that you have a seasonal pattern of depression. Of course, having a stressor such as being without a job every winter will preclude such a diagnosis. Having two episodes of depression during a particular time of the year in the last two years with no non-seasonal episodes and having this pattern of depression over your life time further emboldens a diagnosis of seasonal depression (American Psychiatric Association, 2013). Younger people seem to be more prone for winter depression.

People with seasonal depression usually have “atypical” depressive symptoms such as increased sleep, increased appetite, carbohydrate craving, and weight gain (Praschak-Rieder & Willeit, 2003). In fact, having the above symptoms increases your chances of responding to bright light therapy (Terman et al., 1996). Bright light therapy has been considered as the first-line treatment for seasonal depression for decades now. With bright light therapy, you may notice improvement in your symptoms as soon as 1 week of starting treatment compared to 3 to 4 weeks for antidepressants (Praschak-Rieder & Willeit, 2003). Remission, defined as greater than 50% reduction in depressive symptoms as measured by a depression rating scale, is highest for morning exposure to bright light compared to evening exposure (Terman et al., 1989).

How Does Bright Light Therapy Work?

We don’t know exactly how bright light improves mood. Our brain has specialized centers that keep our biological rhythms (circadian rhythm) of waking, sleeping, melatonin and cortisol secretion, and body temperature in sync with the external 24-hour day/night cycle. In people with seasonal depression, these rhythms may get adrift and it is hypothesized that exposure to bright light restores them. As bright light therapy improves mood in people with non-seasonal depression, it is postulated that bright light may also be regulating other neurotransmitters such as serotonin or stress hormones such as cortisol leading to improvement in depression.

Who Can Benefit from Bright Light Therapy?

The American Psychiatric Association’s guidelines for treatment of major depressive disorder (American Psychiatric Association, 2010) and other studies (Epperson et al., 2004; Sloane et al., 2008) document that bright light therapy is effective in:

• People with major depressive disorder or bipolar disorder and having a seasonal pattern of depression. 
• Non-seasonal major depressive disorder. A study showed that bright light therapy is more effective than placebo either as a stand-alone treatment or in combination with the antidepressant fluoxetine for non-seasonal depression (Lam et al., 2015). Interestingly, in this study, compared to bright light therapy, fluoxetine alone was not effective. However, the small size of the study may have precluded meaningful comparisons between the various active treatments. 
• As an addition to antidepressants and other strategies used to treat depression such as sleep deprivation. Bright light therapy has been shown to speed up the antidepressant response. 
• People with milder depression who don’t meet criteria for major depressive disorder. 
• Pregnant women with depression who don’t want to take medications. 
• People with certain sleep disorders. 

The Practical Aspects of Bright Light Therapy

Quantity of light: The clinical standard for bright light therapy is 10,000 lux. To put things in perspective, 2,500 lux is equivalent to being out on a cloudy day and 10,000 lux is roughly equivalent to being outdoors on a sunny, but not excessively bright day.

Spectrum: White light is recommended for bright light therapy. Any device used for bright light therapy should have a filter for screening out the harmful ultraviolet (UV) light.

Duration and timing of exposure: Thirty minutes of exposure to bright light at an intensity of 10,000 lux in the morning is what is usually recommended. If using a device with lower intensity of 2,500 lux, the exposure is for 2 hours in the morning. As mentioned before, morning exposure has greater effect of deceasing depression compared to evening exposure. It has been suggested that if you don’t see any response after two weeks of treatment, then the exposure should be increased to 30 minutes in the morning and 30 minutes in the evening (Praschak-Rieder & Willeit, 2003). If you don’t perceive any benefit after another two weeks, it may be time to switch over to a different modality of treatment after consulting with your primary care or mental health provider. In one study, the effect of bright light therapy became apparent at four weeks (Lam et al., 2015).

Length of treatment: Bright light therapy is effective if it is used on a daily basis until springtime or at least for five months (the usual duration of seasonal depression). As bright light therapy can be very effective pretty quickly, people may be tempted to stop it, which may increase the chance of relapse of depressive symptoms.

Precautions and Side Effects

If you are leery of taking antidepressant medications or have not tolerated the side effects of antidepressants, then bright light therapy may be a good option for you. Although there are no absolute contraindications of bright light therapy, it is recommended that if you have certain eye conditions such as macular degeneration and skin conditions such as porphyria or solar urticaria, then you need to consult an ophthalmologist or dermatologist before you start bright light therapy. In addition, if you are taking drugs that can cause a photosensitive reaction (examples include certain antipsychotic medications like chlorpromazine, antiarrhythmic drugs like amiodarone, some antimalarial drugs, St. John’s Wort, tetracycline, psoralen drugs, hydrochlorthiazide, sulfonamides, and tricyclic antidepressants), then consulting with your prescribing physician is advisable.

Side effects of bright light therapy are usually minor and transient (Sloane et al., 2008). Common side effects involving the eye include eye strain, blurred vision, seeing spots, glare, and eye burning. Other side effects include skin photosensitivity, headache, nausea, jitteriness, anxiety, and possible induction of hypomanic symptoms. The latter may be true for people with an underlying bipolar disorder and must be closely monitored for in people with this diagnosis. Since most of the commercially available bright light therapy devices that have been used in clinical trials are designed to filter out the ultraviolet light, concerns of permanent damage to eyes or increasing the risk of skin cancer are only speculative.

What to Look for in a Bright Light Device?

The Center for Environmental Therapeutics recommends the following criteria for selecting a light box or high intensity desk lamp for bright light therapy:

• The device should have been clinically tested in independent trials. 
• The device should provide 10,000 lux of light intensity. 
• The device should specify the distance at which it should be placed. The device should be powerful enough to deliver an intensity of 10,000 lux at a distance of 60 to 90 cm. 
• The nature of the light should be white rather than colored. 
• The device should allow the light to be projected at an angle of 30 to 60 degrees with respect to your eyes to avoid eye glare and discomfort (Praschak-Rieder & Willeit, 2003). 
• The device should filter out all ultraviolet rays. 
• The device should be big enough to allow adequate range of motion for your head so that it doesn’t take the eyes out of the therapeutic range of the light. 
• Compare prices and warranty before you make a purchase. 

The take-home message here is that one doesn't have to have seasonal depression to benefit from bright light therapy. Also, for individuals with clinical or sub-clinical depression who prefer not to take medication, bright light therapy is an evidence-based treatment to consider.

To learn more about evidence-based self-management techniques that are proven to work for depression, check out Dr. Duggal's Author Page.

HARPREET S. DUGGAL, MD, FAPA

REFERENCES
American Psychiatric Association (2010). Practice guidelines for the treatment of patients with major depressive disorder (3rd ed.). Arlington, VA: American Psychiatric Association.

American Psychiatric Association (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Association.

Epperson, C. N., Terman, M., Terman, J. S., Hanusa, B. H., Oren, D.A., Peindl, K. S., & Wisner, K. L. (2004). Randomized clinical trial of bright light therapy for antepartum depression: preliminary findings. Journal of Clinical Psychiatry, 65(3), 421-425.

Lam, R. W., Levitt, A. J., Levitan, R. D., Michalak, E. E., Cheung, A. H., Morehouse, R., Ramasubbu, R., Yatham, L. N., & Tam, E. M. (2015). Efficacy of bright light treatment, fluoxetine, and the combination in patients with nonseasonal major depressive disorder: a randomized clinical trial. JAMA Psychiatry, 73(1), 56-63.

Morgan, A. J., & Jorm, A. F. (2008). Self-help interventions for depressive disorders and depressive symptoms: a systematic review. Annals of General Psychiatry, 7, 13. doi: 10.1186/1744-859X-7-13.

Praschak-Rieder, N., & Willeit, M. (2003). Treatment of seasonal affective disorders. Dialogues in Clinical Neuroscience, 5(4), 389-397.

Sloane, P. D., Figueiro, M., & Cohen, L. (2008). Light as therapy for sleep disorders and depression in older adults. Clinical Geriatrics, 16(3), 25-31.

Terman, M., Terman, J. S., Quitkin, F. M., McGrath, P. J., Stewart, J. W., & Rafferty, B. (1989). Light therapy for seasonal affectice disorder. A review of efficacy. Neuropsychopharmacology, 2(1), 1-22.

Terman, M., Amira, L., Terman, J. S., & Ross, D. C. (1996). Predictors of response and nonresponse to light treatment for winter depression. American Journal of Psychiatry, 153(11), 1423-1429.