Light Therapy for SAD: Science, Results & Outlook

Seasonal affective disorder, or SAD, is one of the most common types of depression. Though they don’t continue throughout the entire year, SAD symptoms can take a huge toll on a person during the affected months.

Light therapy for SAD can be a safe and effective modality in the treatment of this seasonal disorder.

What Is Seasonal Affective Disorder (SAD)?

Seasonal affective disorder (SAD) is a common type of depression. But while most types of depression are present throughout the year, SAD is only present at certain times of year.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), SAD occurs when a person experiences major depression that starts and ends during the same seasons every year. The person doesn’t experience this depression during other seasons.

SAD most commonly affects people during the fall and winter months, but it can happen in the spring and summer as well.

Rates of SAD in the general population vary greatly depending on location. These rates largely depend on distance from the equator, winter duration and sunlight patterns.

For example, only about 1% of people in Sarasota, Florida, suffer from SAD. In Fairbanks, Alaska, on the other hand, where winter is long and days are short — sometimes almost nonexistent — the rate climbs to 9%.

SAD symptoms usually appear between the ages of 18 and 30, though they can begin at other ages as well. Women experience SAD four times as much as men.

Symptoms of SAD

The symptoms of SAD are similar to the symptoms of major depression; they just last for a specific time, resolve, and then return at the same time the next year. These symptoms include feeling depressed most of the day, nearly every day, as well as:

  • Loss of interest or pleasure in activities.
  • Low energy.
  • Unintentional weight gain.
  • Difficulty falling or staying asleep, or excessive sleep.
  • Feelings of guilt, hopelessness or worthlessness.
  • Difficulty concentrating or making decisions.
  • Preoccupation with death.
  • Thoughts of suicide.

When SAD occurs in the warmer months, symptoms can include the above, or they can be the opposite. In the summer, for example, agitation, anxiety, restlessness and unintentional weight loss may take the place of low energy and weight gain.

Causes and Risk Factors for SAD

Reduced hours of sunlight in fall and winter are thought to disrupt the body’s internal clock, or circadian rhythm. This reduced sunlight exposure can also lead to a drop in serotonin, one of the brain’s primary neurotransmitters. Levels of melatonin, the body’s main sleep hormone, can also be affected by the change in season.

Although SAD can affect anyone, those with a close relative diagnosed with SAD or major depressive disorder have a higher risk of developing the condition. Another common risk factor is living far from the equator, likely due to the decreased daylight hours in fall and winter.

Between 10% and 20% of people with major depressive disorder year round may also develop SAD, as well as 25% of people with bipolar disorder.

Treatment of SAD

Prescription antidepressants and psychotherapy can greatly help with the symptoms of SAD. In addition, light therapy can play a crucial role in treating the disorder. This is particularly true because of the role that decreased daylight hours plays in SAD.

What Is Light Therapy?

Light therapy shines specific wavelengths of light onto the skin to produce a beneficial response in the body. This can be accomplished at home or in a medical setting.

Red, blue, green or full-spectrum light can be used during light therapy depending on the desired result. Light therapy is generally well tolerated and almost completely free of negative side effects when used correctly.

Our modern culture keeps us indoors in artificial lighting almost constantly. But the body’s cells function more efficiently when they receive adequate amounts of healthy light every day. Scientists have known about the benefits of adequate sunlight for many years, and in more recent years have isolated beneficial wavelengths of light from the damage-causing wavelengths of UV light.

Studies show that these beneficial wavelengths of light produce a wide range of positive effects in the body, such as reducing inflammation, promoting wound healing and resolving sleep issues, to name a few.

Light Therapy for SAD

Light therapy has been used to successfully treat many disorders, from facial acne to Parkinson’s disease. Light therapy for SAD is one of the most well-researched applications of this type of treatment.

Light therapy for SAD usually involves a lamp or light box that emits bright, white light, usually at an intensity of 10,000 lux. The patient spends a set amount of time each morning in front of the lamp to lessen the effects of sunlight deprivation in darker months.

Bright light therapy stimulates cells in the retina of the eye. The retina connects to the hypothalamus in the brain, which controls the body’s circadian rhythm (sleep cycle). Receiving this stimulation to the hypothalamus at the same time each morning helps to regulate the circadian rhythm, promoting high-quality sleep and improving SAD symptoms.

The brain also experiences a boost in serotonin from bright light therapy, which helps to regulate mood throughout the day. The light itself can also help increase energy and alertness.

Other forms of light therapy may also prove useful for mood disorders like SAD. For example, one recent study showed that near-infrared light (NIR) may help improve depressive symptoms.

Light Therapy Products Available for SAD

Because light therapy for SAD is so well established, many light therapy products have been developed for this use.

The Moodozi Light Therapy Lamp has six brightness settings to mimic the sun’s intensity at different times of day. It also has excellent reviews. Customers report increased happiness, boosted energy levels and improved sleep quality.

Northern Light Technologies therapy lamps also help to reduce symptoms of SAD and minimize the “winter blues.” Northern Light Technologies has a variety of options, from floor lamps to desk lamps. You can choose the type that works best for your lifestyle and fits best with your décor.

The HappyLight Luxe made by Verilux is one of the most popular devices for home therapy. It has four intensity settings, a countdown timer and color settings. The design is reminiscent of an e-reader, making it portable and easy to pack up for travel.

The Circadian Optics Lumos Light Therapy Lamp is one of the most inexpensive options on this list. It is also one of the most simple to use, with three brightness settings and one-touch operation. Its compact design and small surface area mean that it fits on almost any surface with ease, but also that treatment time may need to increase to obtain the desired effect.

The Carex Day-Light Classic Plus has a very large surface area for the price, which means users don’t have to extend treatment time beyond the minimum 30 minutes recommended by experts. It also has an adjustable head to project the light downward, is durable, and has a desk lamp setting in addition to the therapy setting.

Be sure to follow all directions on the packaging for the product you choose. Each device is a little different, and you want to make sure you’re getting the optimum benefit!

What’s the Outlook for Patients With SAD?

The low risks of light therapy combined with its high success rates make it an ideal treatment for SAD. Light therapy has the ability to increase serotonin and melatonin production as well as promote energy and alertness.

For patients with SAD, the future with light therapy looks bright!

More Mental Health