To Heal Depression, Turn On The Lights

Adding light therapy significantly increases the benefits of taking antidepressants, researchers have found, and light therapy alone is more effective than just taking a medication for major depression.

For decades, doctors have recommended exposure to strong sunlight or strong sun lamps every morning as a treatment for seasonal affective disorder. Causing depression nearly anywhere north or south of 40 degrees latitude, seasonal affective disorder is an annual onslaught of fatigue, weight gain, insomnia, and bad mood triggered by waning daylight through the autumn months.

Disruption of Melatonin, not Serotonin

Many treatments for non-seasonal affective disorder focus on changing the brain’s use of a mood-related hormone called serotonin. The selective serotonin reuptake inhibitors are medications, such as Prozac, that keep serotonin from being absorbed into neurons, keeping it in the gaps between them so it can play a role in transmitting electrical impulses from neuron to neuron in the brain. The more electrical traffic in the brain, the theory goes, the less depression.

Seasonal affective disorder, however, seems to be caused by a different process. When the eyes sense the visible blue light that is found in sunlight, the brain stops making a substance called melatonin. When the eyes don’t sense blue light, the brain makes the sleep-inducing hormone. The problem with waning daylight hours in autumn is that the brain starts making melatonin earlier and earlier every evening, and stops making melatonin later and later every morning. The result is that people feel sleepy. Their circadian rhythms are thrown off. They don’t have the energy they need for work in the morning, or social activities at night, and “honey I have a headache” becomes the rule for their sexuality.

Treating Seasonal Affective Disorder with Bright Light

Since the problem in seasonal affective disorder is not enough life, the solution, for many people, is more light. It can be enough to go outside for an hour every morning before 9 o’clock if there is bright winter sun. In much of the higher latitudes, however, fall skies tend to be overcast, and by November or December in the Northern Hemisphere or February or March in the Southern Hemisphere, the sun is not completely up for several hours after it’s time to get going for the day.

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To deal with this problem, doctors often prescribe the  use of a device called a light box. The purpose of the light box is make sure the eyes have the sensation of full sunlight. The light used for this treatment does not have to be especially bright. As little as 2,000 lux (somewhere between full daylight and bright sun) is enough to make a difference.  Some light boxes provide 10,000 lux (the equivalent to a sunny day). Bright light stops the production of melatonin, which prevents sleepiness, which aids in all the social interactions and personal decisions that lead to less depression. However, it isn’t just seasonal affective disorder that can be treated with bright light therapy.

Bright Light Lifts Depression Any Time Of Year

A group of Canadian scientists tested the idea that light therapy may be helpful for people who suffer depression any time of year, not just during the months of the year daylight hours are decreasing. The scientists recruited 122 people who had depression for six months between September 2009 and April 2010, dividing them into four groups:

• One group was treated with bright light alone. The volunteers in this group spent 30 minutes every morning in a light box designed to deliver 10,000 lux. They were given a placebo pill to take every evening.
• A second group was treated with Prozac alone. They were asked to spend 30 minutes every morning sitting in front of a negative ion generator (which, the scientists believed, should have no effect on their depression), and to take prescription Prozac every evening.
• A third group was asked to spend 30 minutes every morning in front of the negative ion generator and was given a placebo pill to take every evening.
• The fourth group was asked to spend 30 minutes every morning in the light box and to take an actual Prozac pill every evening.

The team of psychiatrists measured depression with the Montgomery-Åsberg Depression Rating Scale. The rating scale could indicate response, that is, reduced depression, or remission, essentially complete relief from depression. Because some participants were tested as days were getting shorter and others were treated as days were getting longer, the researchers believed day length was not a factor in their results. Each participant followed the protocol for eight weeks.

The results of the study were surprising:

• Volunteers who did not receive any active treatment at all (those who were asked to sit in front of a negative ion generator and given a placebo pill) were more likely to go into remission, that is, completely recover from depression, that people whose only active treatment was Prozac.
• Volunteers were 60 percent more likely to achieve relief with light therapy alone than with Prozac alone.
• The combination of light therapy and Prozac  resulted in a response by 76 percent of volunteers (that is, there was only a 24 percent chance that the combination of treatments would fail completely), and remission by 59 percent.

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The combination of light therapy and Prozac was not a sure-cure for depression, at least not in the eight weeks of the study, but it was more successful than other approaches. Light, however, seems to be more important to treatment than Prozac.

The bottom line is that light therapy is a good place to start in treating depression. It’s not the immediate answer for everyone who has depression, but with the right antidepressant, it is more likely to get results.