Seasonal Affective Disorder: Do Light Visors Work?

What is seasonal affective disorder (SAD)?

Seasonal affective disorder is a recurring form of major depressive disorder that is seasonally dependent. People typically experience depressive symptoms in the autumn and winter months, which tend to improve in the spring. This is called winter pattern SAD.

In rarer cases, people can experience summer pattern SAD, where the onset of symptoms begins in the spring or early summer. 

What are the symptoms?

General symptoms of the seasonal affective disorder include:

• Social withdrawal

• Loss of interest in most activities

• Low mood 

• Fatigue 

• Sleeping more than usual 

• Carbohydrate cravings 

Those with summer pattern SAD often have difficulty sleeping, feel very agitated, and experience poor appetite.

Causes

Research suggests that people with SAD have reduced neurotransmitters¹ in the brain, such as serotonin, which help regulate mood. 

Research also suggests sunlight helps regulate serotonin synthesis in the brain. However, this process doesn't operate properly in people with SAD, leading to decreased serotonin levels in colder months.

Additional research shows that people with SAD may produce too much melatonin², a hormone responsible for maintaining regular sleep-wake cycles. 

For people with SAD, changes in neurotransmitter and melatonin levels mean their bodies cannot adjust to seasonal changes in day length, leading to sleep and mood issues. 

Changes in vitamin D levels during winter may also worsen these issues. Our primary source of vitamin D comes from the body producing it in response to sunlight exposure. 

Vitamin D may help with serotonin activity, so less sunlight exposure in winter may lead to vitamin D deficiencies, further impacting serotonin activity.  

Light therapy for SAD

Light therapy has been recognized as an effective treatment for SAD since the 1980s. 

The treatment involves using artificial light from a light therapy device to simulate sunlight exposure. 

Researchers are not entirely sure how light therapy helps relieve SAD symptoms, but it may help³ in two ways:

1. As sunlight exposure triggers the brain to release serotonin, mimicking sunlight effects through light therapy may also trigger the brain to release it.

2. Light therapy helps regulate melatonin levels, as light exposure inhibits melatonin production. Light therapy may help regulate these chemicals, allowing regular sleep-wake cycles and decreasing depressive symptoms. 

How light visors work for SAD

Different light therapy devices are available. The most commonly used and studied light therapy devices are lightboxes. These boxes are specially designed light fixtures that are brighter than the standard lights and lamps you have at home. 

Light visors are also available, which some people may prefer for convenience. These light devices are attached to a hat/visor, or a band, with the light source fitting just above the eyes. 

Some device brands emit full spectrum wavelengths (all light colors, appearing white). Others emit only specific light wavelengths, such as blue or green. 

The amount of light that a source produces is measured in lux, which is the amount of light a human eye perceives at a certain distance from a light source. 

A clear day produces 10,000-30,000 lux for someone outdoors, an overcast day has around 1000 lux, and a typical interior light produces 50-200 lux. 

Light therapy devices generally produce light ranging from 2500-10,000 lux. 

What does the research show?

Studies⁴ show that light therapy is an effective treatment for major depressive disorder and SAD, and it is effective on its own and in combination with antidepressant medication. 

Studies⁵ have found people experience improvements in energy levels, mood, and concentration after sessions. 

The benefits are short-term, and light therapy sessions need to continue for several weeks to keep feeling the benefits. 

There is limited evidence on the benefits of light visors for treating depressive symptoms, as most light therapy studies focus on lightboxes. 

Early light visor research⁶ showed no evidence for easing SAD symptoms. However, these devices used white incandescent light, which may be less effective than shorter light wavelengths. 

Other research⁷ has found that light visors effectively prevented SAD symptoms in participants. These findings suggest some light visors may produce enough light to be therapeutic for SAD. 

Still, light visors need to be further researched for their measured effectiveness in treating SAD. 

How effective is it?

The FDA does not regulate light therapy devices, so some may not meet clinical criteria for effectiveness. Also, some devices may claim to produce certain lux levels but do not produce them in practice.

Clinical guidelines for light therapy generally recommend exposures of 10000 lux for 30 minutes. However, you can benefit from lower lux exposure if you use the device for longer periods.

A 2019 study⁸ assessed 24 light therapy devices to test whether they satisfied evidence-based clinical guidelines, three of which were light visors. Two visors emitted at least 7000 lux, while the third emitted 6000 lux.

If you are considering light therapy, it's important to select a device that has been studied for effectiveness. Because there is limited research for light visors as a treatment, it may be difficult to find scientific studies.

A healthcare provider can help you identify your light therapy preferences and how long your sessions should be.

It's also important to check in with a health professional before starting light therapy. Severe cases of SAD may require additional medication.

Potential risks

Light therapy is generally considered safe and well-tolerated. However, you may need to avoid light therapy if the following applies to you:

• An eye condition that makes your eyes vulnerable to light damage

• A condition that makes your skin sensitive to sunlight

• Taking medications that make you sensitive to sunlight, such as certain antibiotics

Side effects may include:

• Eyestrain

• Nausea

• Dizziness

• Headaches

• Sleep disturbances

• Hypomanic episodes in rare cases

Consult your healthcare provider if side effects are difficult to manage or do not subside within a few days.

The lowdown

SAD is a type of depressive disorder related to seasonal changes that may cause decreased neurotransmitter levels and disrupted circadian rhythms.

Light therapy may be an effective treatment by replicating sunlight's effects, leading to more normal neurotransmitter levels and sleep-wake cycles.

While light visors can be a convenient and effective option for light therapy, more research is needed to determine their effectiveness for SAD treatment.