How do Full Spectrum Lights Help Seasonal Depression?

Karyn Maier
Karyn Maier

Seasonal depression, also known as Seasonal Affective Disorder (SAD), is a medical condition characterized by symptoms of depression. As the name implies, symptoms begin to emerge during seasonal changes, most commonly in winter. Research indicates that SAD appears to be associated with light, most notably the lack of it. Full spectrum lights may serve as a substitute for missing sunlight, helping to relieve the symptoms of depression.

Seasonal depression is more common in winter and places with significant cloud cover.
Seasonal depression is more common in winter and places with significant cloud cover.

Although SAD is most common in winter, seasonal depression can also occur in summer, in which case, it is known as Reverse Seasonal Affective Disorder. Neither condition should be dismissed as mere cabin fever in winter, or feeling lazy and hazy in summer. In fact, SAD is a genuine mood disorder that, in severe cases, may increase the risk of suicide and require hospitalization.

Full spectrum lights can replace sunshine and relieve symptoms of seasonal depression.
Full spectrum lights can replace sunshine and relieve symptoms of seasonal depression.

Studies have shown that there is a higher incidence of SAD in areas where there tends to be more cloud cover than sunshine. Latitude also seems to affect the rate of occurrence. This has lead researchers and clinicians to theorize that regulated exposure to full spectrum lights may serve as a substitute for natural sunlight and improve symptoms of SAD. While this form of therapy was considered highly experimental not very long ago, many schools, employers, and public facilities now use these lights to ward off the winter blues.

Feeling depressed is a common symptom of seasonal affective disorder.
Feeling depressed is a common symptom of seasonal affective disorder.

Full spectrum lights seem to provide several benefits. For one thing, mood appears to be affected by how well people can see — perhaps even by the mechanical processes occurring in the eyes. In daylight, the cones of the eyes are activated, as opposed to forcing the ocular rods to compensate for night vision. Lights that include the full spectrum provide the closest simulation to natural sunlight by emulating the wavelengths of the sun’s zenith, the point when it is directly overhead in the sky at noon. There is no risk of exposure to ultraviolet light, however, which can harm skin and eyes.

Light also plays a role in regulating circadian rhythms, the human body’s internal alarm clock that signals when it’s the appropriate time to rise in the morning and retire to bed in the evening. This is evidenced by the fact that people who work “graveyard shifts” tend to experience SAD more frequently, since they often leave for work and come home in the dark. This scenario is likely to confuse the brain from properly distinguishing between night and day, resulting in a decrease in melatonin production. Full spectrum lights can help to minimize this effect by stimulating an increased release of this “feel good” hormone.

People should be aware that therapy with full spectrum lights is not the same as sitting under ordinary bright light bulbs purchased from a hardware store. Full spectrum refers to white light with a luminance of 2,500 to 10,000 lux, with the first number closely representing daybreak and the second full daylight. As a treatment, exposure to such lights is typically done while sitting in a light box for 30 to 60 minute intervals.

In addition to light therapy, people with seasonal affective disorder (SAD) may benefit from walking outdoors for one hour each day.
In addition to light therapy, people with seasonal affective disorder (SAD) may benefit from walking outdoors for one hour each day.
Karyn Maier
Karyn Maier

Contributing articles to wiseGEEK is just one of Karyn’s many professional endeavors. She is also a magazine writer and columnist, mainly for health-related publications, as well as the author of four books. Karyn lives in New York’s Catskill Mountain region and specializes in topics about green living and botanical medicine.

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Discussion Comments


I got my light from the Amazon store. It helps.


I know that Reverse Seasonal Affective Disorder is not nearly as common, but I have a friend who must struggle with this.

I have a hard time comprehending this, but she actually prefers days that are dark and overcast and doesn't enjoy the bright sunny days. This is just the opposite of someone who struggles with SAD and I wonder what kind of treatment they recommend for someone who has this?


@bagley79-- You are fortunate you have this type of lighting at your work. It would also be interesting to see if there are less sick days used because someone is feeling down or depressed.

Once I tried getting some of the brightest light bulbs I could find and sitting under them for awhile, but I don't think it really did anything. I think I am going to have to break down and buy something or check into some kind of full spectrum light therapy. I really struggle with this seasonal depression every year.


I don't work the "graveyard shift" but have a considerable drive to and from work each day. There are weeks at a time during the winter when I leave home when it is dark and return home in the dark. I feel like I go months without really seeing any sunshine.

This can start to wear on you after awhile and bring you down. I am fortunate that my employer had some full spectrum LED lights installed at our workplace a year ago.

I notice that the light at work is much brighter than the light I have at home. This makes it easier to focus and concentrate and I am sure this is one reason they had these installed. It would be interesting to see if work production has increased since they installed these lights.


@letshearit-- A few years ago I bought a full spectrum lamp and think it has made a difference in my mood during the long winter months. I would say that my seasonal affective disorder is pretty mild, but I got tired of feeling sad and blue all the time.

I make it a point to spend at least 30 minutes a day under this lamp and find that I really look forward to that time. When I am done I can feel a lift in my spirits and continue on with the rest of my day.

Some people may say this is just in my head, but as long as I keep feeling better by using it, I am going to keep it up. Everyone may react a bit differently, but I don't think you have much to lose by giving it a try.


Has anyone tried full spectrum bright light direct to brain? Like the Valkee bright light headset?


There was an article in Martha Stewart Living about full spectrum light bulbs, so they do exist. You may have to do some research though to find out where you can buy them in your country.

On a side note, does anyone know if there are any foods you can eat to help seasonal depression?

It would be great if you could do something like this alongside full spectrum light treatment.


Is getting full spectrum light treatment expensive? Or is there something that you can do at home to have the same effect?

This sounds like a great solution to battling SAD, especially living in a country that has a ton of cloud cover throughout the year.

Does anyone know if there are light bulbs that can be purchased to replace your regular bulbs?

I imagine that if you just replaced your regular bulbs it would have the same benefits as a light box.


I am curious to know how well full spectrum lights help treat seasonal depression. Does anyone have experience using this as a treatment?

I know SAD is mainly an imbalance in the body caused by fluctuating hormones that are impacted by our environment.

Our levels of serotonin and melatonin play a big part in how SAD develops. Serotonin is responsible for keeping us calm and focused, while melatonin helps to regulate our sleep.

Both of these hormones are controlled by how much light we receive, so I imagine with proper full spectrum light treatment that it would indeed help.

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