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Light Therapy: Does it really brighten your winter day?

The Efficacy of Light Therapy in the Treatment of SAD


Jenna Rogers




            Do you ever get the blues in the winter? Do you seem to feel more tired, fatigued and tend to eat more? If you persistently have these symptoms every winter then you may have a form of Seasonal Affective Disorder or SAD. “It's estimated that about 6 percent of Americans suffer from winter SAD, and another 10 percent to 20 percent may experience mild SAD symptoms” ( There is no cure for this disorder however there are treatments that can improve symptoms. The most common form of treatment is light therapy that can be easily applied through a light box. Even though light therapy is the most common and standard form of therapy for SAD, there are still many unanswered questions about the true efficacy of the treatment and which applications of light therapy are most efficient.



What is Seasonal Affective Disorder?


            Seasonal Affective Disorder (SAD), more commonly known as the “winter blues,” effects about half a million people. It is a form of winter depression that can range from mild cases causing discomfort to more serious cases that can inhibit people’s daily lives. SAD effects people during the winter months and can extend from September to April because of the decrease of daylight hours during the day. (




Biological causes of SAD                 


            SAD is a mood disorder that is caused by the effects that the seasonal variations in sunlight have on our “biological clocks” and chemicals in the brain. Our internal clock or our circadian rhythm controls the body’s sleep cycles and is regulated by the pineal gland’s excretion of the hormone melatonin. The pineal gland is located in the brain and regulates when we are awake and when we are asleep by the amount of melatonin that it releases into the body. Part of this regulation is based on a 24 hour cycle and the amount of light exposure. Darkness stimulates the pineal gland to secrete higher levels of melatonin. Therefore, we become tired and fatigued when it becomes dark outside because the body’s circadian rhythm is preparing us for sleep.


However, during winter months the decrease of daylight hours stimulates the pineal gland to release higher levels of melatonin causing us to be tired and fatigued during times in the day where there should be heightened activity. The shortened days in the winter cause our internal clocks to be out of line with our daily activities creating the discomforting and often debilitating symptoms of SAD (




Those diagnosed with SAD have an increase of melatonin in their bodies and can have varying degrees of symptoms. Some patients diagnosed with a mild case of SAD only report of tiredness and fatigue. However, some face more life inhibiting symptoms:




These symptoms can also result in a diagnosis of general depression but if the symptoms reoccur seasonally then the patient is diagnosed with SAD. The symptoms of SAD also decrease or go into remission typically after February and often disappear totally during the summer months. The reduction of symptoms in the summer months when the hours of daylight increases supports the current research on the primary cause of the disorder, the amount of light exposure.



Possible Treatments


The first treatment that would be prescribed to someone diagnosed with SAD would be to increase the amount of natural light exposure during the day. If natural light exposure is not available or effective then phototherapy or light therapy is used and in some extreme cases, antidepressant drugs are prescribed.  



Light Therapy    



Light therapy is prescribed to patients in hopes to address the lack of sunlight in the winter to reduce symptoms of SAD and to decrease levels of melatonin in the body.


Light therapy is most commonly administered to patients through a light box. Light boxes can vary in the type and strength of wave emitted. The current standard form of light used in light therapy and emitted from light boxes is bright white light.


Most light box designs today consist of a fluorescent light on a reflector which is shielded by a plastic screen. ( They are designed to be easy and convenient to use and treatment can be administered by sitting in front of a light box while doing daily activities.




Light therapy’s goal is to reverse the effects of SAD. These can include:


Side Effects:


Currently, light therapy is the leading treatment because it causes fewer side effects than antidepressant drugs. Some side effects that are rare but can occur are:




Is Light Therapy Effective enough to be the Only Treatment for SAD?


Past studies have shown bright light therapy (BLT) to be an effective treatment in reducing symptoms of SAD with tolerable side effects. However, a recent study by the University Hospital for Psychiatry in Austria (Pjrek et al 2004) has shown that such studies have used small study groups therefore possibly skewing results. Their more in-depth study shows that BLT only helps reduce symptoms in about a third of patients who use it. Five hundred and fifty three outpatients from a clinic in Austria who were diagnosed with winter SAD were used for the expanded study. All of the subjects were given a month long trial of BLT. They were instructed to use BLT every morning for at least 30-45 minutes. Forty- nine percent of the subjects in the sample were noted as using psychopharmacologic medication as well as BLT.


Results showed that BLT did not suffice as a treatment for the reduction of SAD symptoms in a large proportion of the sample. In over one third of the subjects, antidepressant drugs were needed to facilitate the decrease of SAD symptoms. This was apparent in many subjects not experiencing sufficient relief to depressive symptoms even though there was some improvement. However, BLT showed to be most beneficial in subjects with atypical symptoms. Some patients didn’t feel the effects of BLT because they didn’t comply to the prescribed use due to convenience difficulties and conflicts with coping with other psychological disorders. This study shows that light therapy can help decrease some symptoms but the frequency and consistency of reduced symptoms is not enough to establish light therapy as the only form of treatment in every case of SAD.


Even though research has not shown light therapy to be effective enough to be the sole treatment for all patients with SAD, it is still able to reduce symptoms in some cases of SAD. Physicians still prescribe its use to patients but they may accompany BLT with antidepressant drugs. According to the National Mental Health Association, “Phototherapy or bright light therapy has been shown to suppress the brain’s secretion of melatonin. Although, there have been no research findings to definitely link this therapy with an antidepressant effect, many people respond to this treatment” ( ).


Does light therapy really reduce symptoms or is it all in our heads?


As research has developed on the effectiveness of light therapy, the question of why symptoms of SAD are reduced arises. Antidepressant effects can arise in a patient due to a biological effect on hormone levels or it can be a cause of the patient’s belief that the light therapy will be effective. This placebo effect is usually presented as an obstacle that experimenters must account for and overcome. Past studies have used different strengths of light but subjects usually see beyond this attempt to control placebo effect as they expect a brighter light to be more effective.


A study by the Archives of General Psychiatry (Eastman et al 1998) tested the differences between morning and evening applied light and found a way to control the placebo effect. They were therefore able to conclude that BLT does have an effect on symptoms of SAD beyond the placebo effect.

Subjects with SAD and not taking any antidepressant drugs were recruited and randomly assigned to four treatment groups, morning light, morning placebo, evening light, evening placebo. The placebo treatment was an ion generator that resembled a light box and those in the placebo group had the same treatment of 1.5 hours of light exposure and similar sleep schedules to those in the light groups. Expectation ratings were analyzed as well as the effects of morning and evening light administration. Analysis of expectation ratings between placebo groups and light groups showed that there was no significant difference in expectation of effects between the groups. Therefore this study identified an appropriate placebo effect control and proved that bright light therapy has an antidepressant effect on SAD patients beyond the placebo effect.


Light therapy does have an antidepressant effect on those with SAD that cannot be linked to placebo effects of the treatment because the patient believes it will work. Therefore BLT must have a biological effect that reduces SAD symptoms.


Administering Light therapy Through a Light Box


How to use your light box


If light therapy is prescribed to help reduce symptoms of SAD, many factors in how to administer the light therapy must be taken into account. Apollo Health, a leader in light therapy and a marketer for light boxes proposes appropriate administration of phototherapy. A patient using a phototherapy light box is to expose oneself to BLT:



            Does it matter when BLT is administered?       



The same study by Archives of General Psychiatry (Pjrek et al 2004) that determined an appropriate control for the placebo effect also tested the differences that the time of light therapy administration can have on its effectiveness. The same experimental design was used with subjects randomly assigned to four groups with different treatment times of morning light, morning placebo, evening light, and evening placebo. The placebo was a light box simulator that proved to have no effect on the effectiveness response of the subjects. Each subject was exposed to a week of treatment followed by 4 weeks of their group treatment. Sleep schedules were given to the subjects and subjects were checked in on a weekly basis.


BLT was shown to be a more effective than the placebo but not until the third week. At week 3, there was a greater response to morning light than evening light but at the conclusion of the experiment, there were no significant differences between the four groups. However, when remission rates were examined, it was shown that morning light produced the best response rates in the following weeks after the experiment. Morning light was found to be slightly more effective than evening light. This could be due to morning light advancing circadian rhythms and helping sleep schedules where evening light delayed the circadian rhythm making it more difficult to adjust.


Therefore, it does matter when BLT is administered and many physicians will prescribe patients to administer BLT during their morning routine instead of before they go to bed.



Light therapy products emit different wavelengths of light: is there a greater effect as wavelength shortens?


Over the years, there has been various light therapy products available that claim to emit various types of light. Some of the different types of light that have been emitted from light boxes include UV light, bright white light, and red light. Currently the claim is that blue light’s short wavelength is the most effective form of light.


Apollo Health, a light therapy company has created a new form of light therapy that is based on the claim that blue, short wavelengths are more effective and provide more timely results to the symptoms of SAD than the current standard bright white light. Apollo Health has developed an idea that a specific band of light wave called Bluewave has the greatest effects in reducing the amount of melatonin released (


Bluewave, according to Apollo Health, has benefits that bright white light doesn’t provide such as it is:


            The Society of Biological Psychiatry (Glickman et al 2006) did a study to test the efficacy of short wavelength light therapy on the symptoms for SAD by comparing blue wavelength to red wavelength effects on sleeping patterns. Thirty subjects were recruited and randomly assigned to either a short, blue wavelength light box or a long, red wavelength light box. The subjects were assigned to perform the light treatment for 45 minutes daily in the morning for 3 weeks. Progress was recorded through a sleep time log.


            Results showed that short, blue wavelength light boxes significantly performed better when remission rates were examined. The effects of blue light were similar to those in the current standard bright white light treatment. Blue light also proved to have fewer side effects than bright white light because of the reduced light intensity. Even though blue light was not compared to bright white light, blue light shows promise to be more effective than or at least as effective as bright white light because shorter wavelengths were proven to be more effective than longer wavelengths.


            Light therapy technologies such as Bluewave are legitimate and effective as it has been proven that light with shorter wave lengths such as blue light has more or the same efficacy as the standard bright white light. Blue light also provides benefits such as fewer side effects that affect the eyes because of the reduced intensity. Therefore, products such as Bluewave may become the standard form of light therapy in the future.


For those patients who prefer the intensity and projection of bright white light but want the fewer side effects and proficiency of the blue light, products are being developed such as Britewave. Britewave combines Bluewave and bright white light in a light box and provides the user with the intensity and brightness of a full spectrum light but also gives the benefits of the Bluewave (





Light therapy has been proven as an effective form of reducing symptoms of SAD. Even though light therapy can be effective in reducing symptoms of SAD, it is not the case in all patients. The particular patient must be evaluated by a physician to determine if light therapy will be effective taking into account lifestyle and other disorders. If using light therapy is appropriate for your case of SAD, then precaution must be taken in which light therapy application would be the most effective. A patient using light therapy must pay attention to using the therapy in the morning and choosing a light box that emits either bright white light or blue light to gain the therapy’s highest efficacy. According to current and past research, light therapy seems to be an appropriate and often effective treatment of SAD.  






Eastman, C., Young, M., Fogg,L., Liu, L., Meaden,P. (1998). Bright Light Treatment of Winter

Depression: A placebo- controlled trial. Arch Gen Psychiatry, 55, 883- 889.


Glickman,G., Byrne, B., Pineda, C., Hauck, W., Brainard,G. (2006). Light therapy for seasonal

affective disorder with blue narrow- band light- emitting diodies (LEDs). Biological

Psychiatry, 59, 502-507.


Pjrek, E., Winkler, D., Stastny, J., Konstantinidis, A., Heiden, A., Kasper,S. (2004). Bright light

therapy in seasonal affective disorder- does it suffice? European

Neurophsychoparmacology, 14, 347-351.



Websites Referenced:


Apollo Health. Britewave Technology.


Apollo Health. Bluewave Technology.


Apollo Health. Light Therapy: What is Effective.


Canadian Mental Health Association. Seasonal Affective Disorder.


Lam, R. W. (1994).Current Opinion in Psychiatry



MayoClinic. Seasonal Affective Disorder (SAD)



Medicomm. Light therapy.


National Mental Health Association. Seasonal Affective Disorder.


The Seasonal Affective Disorder Association. What is SAD?



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