Light Therapy for Depression

I have severe pain and trouble walking, I push myself 
to go outside in the sunlight. It makes the whole day 
change and lessons the intensity of pain. 
Of course it's hard for me to just sit there 
so I begin planting or just visiting my flower family. 
It truly works for me.

Marcella Floyd

About Light Therapy

What may be a good treatment for one type of depression may be good for another. Take light therapy for depression, for instance. Doctors have successfully treated seasonal affective disorder (SAD), a mild depression caused by reduced exposure to sunlight in winter months, with light therapy – spending a prescribed amount of time each day in front of artificial light that replicates the spectrum of sunlight. Light therapy may one day be used for general depression, too.

Researchers at the University of North Carolina at Chapel Hill School of Medicine discovered an interesting finding after reviewing 20 studies. “We found light therapy is an effective treatment not only for SAD but other types of depression as well,” says study leader Robert Golden, MD, professor and chairman of psychiatry.

Dr. Golden and his researchers reviewed studies of people aged 18 to 65 with a diagnosed mood disorder. Participants were grouped into four categories: bright light for SAD, bright light for non-seasonal depression, dawn simulation (simulating early dawn with artificial light at lower levels) for SAD and bright light with antidepressants for non-SAD. In every category, participants’ moods improved, with greater improvement found with a combination of antidepressants and light therapy. “The findings [for light therapy] are as strong or as striking” as those for conventional medications used as treatments for depression, according to Dr. Golden.

More studies are needed to provide definitive evidence on the effectiveness of light therapy for depression. Still, Dr. Golden says, “Light therapy may be a reasonable alternative to more established forms of treatment, including medication and psychotherapy.”

How much light are you getting?

Light therapy can treat more than just winter depression, though that's the main use. Here's why:  the amount of light reaching your eyeball from interior lighting is far less than the amount from the real thing. So unless you are outside much of the day in the winter, you are relying on electric light for your photons (in summer, there is so much light, most people get enough, even if they are indoors during their work hours). The following table shows you just how much less light you receive, indoors versus outdoors (Lux is a standard unit of light flow):

Brightness Values:
-        Candle light at 20 cm       10-15 Lux
-        Street light                       10-20 Lux
-        Normal living room lighting    100 Lux
-        Office fluorescent light    300-500 Lux
-        Halogen lamp                   750 Lux
-        Sunlight, 1 hour before sunset            1000 Lux
-        Daylight, cloudy sky        5000 Lux
-        Daylight, clear sky           10,000 Lux
-        Bright sunlight                 > 20,000 Lux

When to consider light therapy

Light therapy may be a treatment option for you if:
  • You don't want to take medications such as antidepressants
  • You can't tolerate the side effects of antidepressants
  • You've tried antidepressants but they haven't been effective
  • You want an alternative to psychotherapy
  • You're pregnant or breast-feeding and are concerned about the effects of antidepressants on your developing fetus or baby
  • You don't have insurance coverage for mental health services
  • You lack access to mental health services

Conditions light therapy may help

Conditions and problems that may benefit from light therapy include:
  • Seasonal affective disorder
  • Nonseasonal types of depression
  • Obsessive-compulsive disorder
  • Premenstrual dysphoric disorder
  • Postpartum depression
  • Jet lag
  • Certain sleep disorders
  • Shift-work problems
Keep in mind that light therapy hasn't officially been approved by the Food and Drug Administration as a treatment for seasonal affective disorder or other conditions. But many mental health providers consider light therapy the main seasonal affective disorder treatment.


Risks and side effects associated with light therapy are uncommon but can happen. They can include:
  • Eyestrain
  • Headache
  • Agitation
  • Nausea
  • Vomiting
  • Irritability
  • Fatigue
  • Dry mouth
  • Sleep problems
  • Mania
When side effects do occur, they're usually mild. They may go away on their own within a few days of starting light therapy. You also may be able to manage these problems by reducing treatment time, moving farther from your light box, taking breaks during long sessions, or changing the time of day you use light therapy. Talk to your doctor for additional help and advice, or if your side effects don't go away or get worse.

Who shouldn't use light therapy?

Some light boxes don't filter out or shield harmful ultraviolet (UV) light. UV light can cause skin and eye damage. Don't use light therapy without consulting your doctor first if:
  • Your skin is sensitive to light
  • You take medications that react with sunlight, such as certain antibiotics or anti-inflammatories
  • You have an eye condition that makes your eyes vulnerable to light damage
Cautions for bipolar disorder, severe depression

Light therapy may trigger episodes of mania in people with bipolar disorder. Also, although rare, some people, particularly those with severe forms of depression, develop thoughts of suicide after light therapy. Be sure to talk to your doctor or mental health provider before starting light therapy or at any time during treatment if your condition gets worse.

What you can expect

Starting light therapy

The general recommendation for most people with seasonal affective disorder is to begin treatment with light therapy in the early fall, as soon as your symptoms start. Treatment generally continues until spring, when outdoor light alone is sufficient to sustain a good mood and higher energy.

Some people experience seasonal affective disorder in the summer. And others who typically have winter depression may notice symptoms during prolonged periods of cloudy or rainy weather during other seasons. You and your doctor can adjust your light box treatment based on the timing and duration of your symptoms.

For other conditions, talk to your doctor about the best time to begin light therapy.

During light therapy

During light therapy sessions, you sit or work near a light therapy box. To be effective, the light from the light box must enter your eyes indirectly. You can't get the same effect merely by exposing your skin to the light. While your eyes must be open, don't look directly at the light box because the light can damage your eyes.

Light therapy sessions are generally done each morning after you awake. Some light therapy boxes, however, are dawn simulators — they turn on in the morning while you're still asleep and gradually get brighter until you wake up.

Three key elements for effective light therapy

Light therapy is most effective when you have the proper combination of duration, timing and light intensity:
  • Duration. When you first start light therapy, your doctor may recommend treatment for shorter blocks of time, such as 15 minutes. You gradually work up to longer periods. Eventually, your light therapy typically involves daily sessions ranging from 30 minutes to two hours, depending on your light box's intensity.
  • Timing. For most people, light therapy is most effective if used in the morning, after you first wake up, rather than during the evening. Doing light therapy at night can disrupt your sleep. Because light therapy seems to work best in the early morning, you may need to wake up earlier than you normally would to match treatment with your natural biological rhythms. You may find it hard to wake up early, especially if depression leaves you feeling lethargic. Your doctor can help you find a light therapy schedule that works for you.
  • Intensity. The intensity of the light box is recorded in lux, which is a measure of the amount of light you receive at a specific distance from a light source. Light boxes for light therapy usually produce between 2,500 lux and 10,000 lux, with 10,000 lux being typical. In contrast, the lighting in an average living room in the evening is less than 400 lux, while a bright sunny day may register 100,000 lux. The intensity of your light box may also determine how far you sit from it and the length of time you need to use it. The 10,000 lux light boxes usually require 30-minute sessions, while the 2,500 lux light boxes may require 2-hour sessions.

Light therapy probably won't cure seasonal affective disorder, depression or other conditions. But with safe and effective light therapy, your symptoms can get better. You may feel better about yourself and life again, and have more energy.

Light therapy can start to improve symptoms within just a few days. In some cases, though, it can take two or more weeks.

Light Therapy Development

In the early 1980’s, scientists researching depression noted a consistent pattern of symptoms becoming more severe in many patients during the long winter months, particularly in the northern hemisphere. Significantly these symptoms eased or disappeared completely as the longer summer days returned.

In 1982 The National Institute of Health (NIH) identified winter depression and coined the term, ‘SAD’ for Seasonal Affective Disorder.

The scientists found that 'SAD' was related to an imbalance in the body's natural circadian rhythms. The Circadian rhythm, or the body’s inner clock governs the timing of sleep, hormone production, body temperature, and other biological functions.

In 1984 these pioneering scientists discovered that exposure to bright white light is very effective at treating seasonal affective disorder.

For many years doctors had relegated light therapy to the periphery of credible science. It wasn’t until 2001 that researchers from NIH, Thomas Jefferson Medical University and Apollo Health fully understood how exposure to specialized bright light, stimulates the production of brain chemicals to relieve the symptoms associated with seasonal depression.

Dr. George Brainard’s team at Thomas Jefferson Medical University, identified a photo receptor in the human eye, responsible for reacting to light and controlling the production of melatonin.

They found specifically that light in the range of 447-484 nm (nanometers) is responsible for suppressing melatonin production and shifting circadian rhythms. Indeed, this particular bandwidth of light is up to ten times more effective than other wavelengths. We now know this technology as BLUEWAVE. The light therapy is considered as an effective treatment for body clock corruption as well, helping to the patients fighting sleep disorders

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