Full Spectrum Light

Medically reviewed by Julie Dodson, MA, LCSW

Updated April 21st, 2025 by BetterHelp Editorial Team

You may have heard of full spectrum light therapy before and wondered if it's something that can help you. Another kind of light therapy for depression, known as light box therapy, is also available and may be effective for treating a variety of conditions. When it comes to mental health, full spectrum light therapy is generally used to treat people who are experiencing seasonal affective disorder (SAD), but it may help those with other forms of depression as well.

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Light therapy can help ease depression

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How does full spectrum SAD light therapy work?

When people undergo full spectrum light therapy, they have a light box that they use as their treatment. This box emits a light that a person stands or sits in front of.

Using a SAD lamp, which features a full spectrum light bulb, can be a great option for individuals who experience seasonal depression. Full spectrum light is designed to replicate the natural sunlight essential for a healthy lifestyle. When positioned in front of the lamp, you can close your eyes or leave them open, but avoid looking directly at the light. Note that this isn't an instant solution; however, with consistent use, you may notice an improvement in your depression symptoms and overall mental health.

Three essential components come into in full spectrum light therapy. The first is light intensity, known as lux, which indicates the amount of light received during therapy sessions. Many different types of full spectrum lights are available, but for SAD (seasonal affective disorder), a standard 10,000 lux light is recommended when positioned between 16 and 24 inches away from it. It's advised to consult your doctor before purchasing a full spectrum light, as they can provide specific recommendations based on your needs.

Other factors that can impact the effectiveness of your full spectrum light therapy session are the duration and the timing. These are also factors that you can talk to your doctor or therapist about. Many people feel that it benefits them to do light therapy first thing in the morning. However, this is something that your therapist can help you determine for your particular situation. The duration of your therapy sessions depends on the type of light and the amount of lux.

The science behind full spectrum light therapy suggests that consistency is important to its success. For shift workers or people with busy schedules, compact full spectrum light therapy devices may be a great option. These devices can be used in a shorter amount of time and may have different types of light therapy, such as blue or red light. However, it's important to consult with your doctor or therapist to determine the appropriate type and duration of full spectrum light therapy for your needs.

When did full spectrum SAD therapy become popular?

People have believed in the power of sunlight for healing for centuries. Natural light has been used as a medical treatment for as long as people can document. However, full spectrum light boxes didn't start to become popular until the 1990s. Since then, the number of success stories from the use of full spectrum light has continued to keep it in the spotlight.

Who needs full spectrum SAD therapy?

Full spectrum light therapy can be used to treat several different diseases and disorders, but for this article, we're going to focus on mental health. The people who can benefit the most from full spectrum light therapy tend to be those who experience depression, especially seasonal affective disorder. However, it can also be used for other types of depression and to help people with circadian rhythm sleep disorders or those who travel frequently and experience jet lag.

Also, while blue light from screens can suppress melatonin (which helps with sleep), research has shown that exposure to blue light during the day can improve alertness.

The symptoms of seasonal affective disorder

The symptoms of SAD tend to be the same as those of other forms of depression. The main differentiator is that SAD typically occurs only during certain times of the year. For the majority of people, this will be during the winter (often referred to as the winter blues), but there are also people who experience it during a different season.

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This means that the symptoms of SAD usually start around the same time every year and leave around the same time every year. It can work like a cycle, and it's something that you're able almost to predict.

Symptoms of depression may include feeling sad or down but can also include feeling angry and more irritable. You may experience changes in your sleeping pattern and in your desire to eat. Some people sleep more, but others sleep less. Similarly, some people eat more, but others eat less. Many people experiencing depression also start to withdraw from friends and family and the things that they enjoy in life. It can almost make them want to shut down.

Why can't we just go outside for full spectrum light?

If full spectrum light therapy is really just giving people artificial sunlight, why can't they just go outside to take in actual sunlight? The best light is natural sunlight. However, in this day and age, there are many people who experience a shortage of the natural sunlight that they need. This could be people who work long hours and find themselves leaving for the office when it's dark in the morning and not leaving until it's dark at night.

Full spectrum light therapy also comes into play for SAD in states that experience less sunlight during the winter months. Many people are affected by SAD between fall and early spring. This is because many states have more cloudy days in the winter, and when you combine that with shorter daylight hours, it can lead to depression for some people.

Unlike being outside where the amount of natural sunlight can vary, light therapy boxes can provide a consistent and controlled amount of full spectrum light exposure for those who may not be able to get enough natural sunlight throughout the day.

How to get a SAD light therapy box

You can buy a SAD light therapy box online or in stores without having any type of a prescription. However, it’s still recommended that you talk to a doctor or therapist before getting one.

There are some adverse side effects that you can experience if you do not use a full spectrum light therapy box correctly. There are also some people who shouldn't use light therapy boxes. Therefore, if you buy a light box without talking to a doctor first, you could see a decline in your health instead of the benefits that you’re looking for.

Light therapy boxes can range in price from $20 to thousands of dollars. This is another reason why you might want to talk to a professional before buying one. Buying the cheapest box may not be the best option for your mental health challenges, but you may not need to spend thousands on a light box, either.

Another factor that you might consider when purchasing a light therapy box is UV rays. There are many light boxes available that are UV free. Some light boxes mimic sunlight without using UV rays.

If this all sounds a bit overwhelming, you may also find comparison guides helpful in making your selection. News outlets including The New York Times, The Huffington Post, and Good Housekeeping, among others, walk through the differences across makes and models offered by leading manufacturers.

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Light therapy can help ease depression

Meet with a licensed therapist

What should I do if I think light therapy would work for me?

If you think that full spectrum light therapy is right for you, it may be helpful to consult with a therapist who specializes in or has experience with this type of treatment. They can provide guidance on the course of therapy that would be best for your specific needs.

During your initial therapy session, you can talk to the therapist about types of treatment that are available and tell them why you would like to try light therapy. They may give you their opinion on what treatment path will be right for you. For some people, light therapy is the only form of treatment that they need. However, other people also benefit from other forms of treatment, such as psychotherapy along with light therapy sessions.

Does this therapy work?

Some people are suspicious that light therapy can help with their depression. It's important that to remember that light therapy is not going to be the right option for everyone. It is not a cure-all for depression. However, some people experience significant results in improving their mental health and levels of depression through full spectrum light therapy.

Takeaway

If you are experiencing seasonal affective disorder (SAD) or the winter blues, light therapy could be the right option for you. However, you might also benefit from therapy. If you’re not feeling well enough to go to a therapist’s office, you might try online therapy, which research has shown to be just as effective as in-person therapy. With BetterHelp, you can contact your therapist from the comfort of your home via videoconference, phone, or in-app messaging. You can also be matched with a therapist experienced in SAD or depression. Take the first step and reach out to BetterHelp today.

Frequently asked questions

Read more below for answers to questions commonly asked about this topic.

What is light therapy and what should I expect from it?

Full spectrum light therapy is generally used to treat people with seasonal affective disorder (SAD), but it can also help treat other types of depression, sleep disorders, and jet lag. The treatment involves a box that replicates natural sunlight. This is believed to cause a chemical change in the brain that lifts mood and offers relief from other symptoms of seasonal affective disorder. Full spectrum lighting refers to the type of artificial sunlight used in this therapy.

How do you use lighting in SAD therapy?

In SAD therapy, a person sits in front of a box with a full spectrum bulb that replicates natural sunlight. The standard intensity for treating SAD is 10,000 lux when a person is sitting between 16 and 24 inches away from the box. Typically, doctors recommend sitting in front of the full spectrum light box when you first wake up in the morning for 20-30 minutes. Since these full spectrum light bulbs mimic natural light, they can offer a convenient way to experience the benefits of light when real sunlight is less available.

Some manufacturers sell sunrise alarm clocks, alarm clocks that ease you awake using artificial sunlight (rather than sound) over a 30-minute period. Fans of sunrise alarm clocks say the approach is a less jarring way to start the day.

Does full spectrum therapy really work on people?

Bright light therapy is considered a key treatment option for seasonal affective disorder (SAD). Although this form of light therapy may not be the right option for everyone and is not a cure-all for depression or mood disorders, many people who experience SAD report significant results. For others, this therapy may be more effective when combined with another treatment, such as counseling or medication.

What is the best full spectrum lamp for seasonal affective disorder?

The Center for Environmental Therapeutics offers guidance that can help you decide which kind of lamp to purchase to help treat seasonal affective disorder (SAD). Factors you may want to consider in your decision include intensity, safety, source, cost, style, and dual purpose (some lights can double as desk lamps). In general, the center suggests that the best lights have been tested in peer-reviewed, placebo-controlled clinical trials; provide 10,000 lux illumination; include a diffusing screen that filters out ultraviolet rays; project the lamp downward to avoid glare; are at least 15” wide and 12” high; and emit a white or soft white light. Some people may also prioritize finding a flicker-free bulb or have other preferences based on their needs.

When choosing between lamps, you may also find comparison guides helpful in making your selection. Articles may provide a side-by-side comparison guide for leading full spectrum light boxes.

Does light therapy really work for wrinkles?

Beauty magazines and blogs have written extensively about the possible benefits of light-emitting diode (LED) skin devices. Some research suggests there is truth to claims that these emerging products could help reduce wrinkles, redness, and other signs of aging, but more research is necessary to fully understand their effectiveness. Keep in mind that products advertised as therapeutic for skin are not the same as those used to treat depression.

Is full spectrum light dangerous?

Full spectrum light is considered safe, but as with any treatment, it’s important to maintain a dialogue with your doctor if your symptoms are not improving or they are getting worse.

For instance, people with certain eye conditions should speak with their doctor prior to beginning treatment. Side effects are generally mild but could include eye strain, headache, nausea, irritability, mania, euphoria, hyperactivity, or agitation associated with bipolar disorder. Also, the Skin Cancer Foundation warns against using tanning beds as a means to attempt to treat SAD symptoms.

How long does it take for full spectrum light therapy to work?

The best way to know whether therapy is working is to monitor your mood. Many people respond to bright light therapy within two to four days, but each situation is unique.

Is full spectrum light the same as daylight?

To understand full spectrum light and daylight, it’s important to clarify a range of related terms and concepts regarding the light spectrum. Full spectrum light, as a type of light, refers to light that spans the spectrum of electromagnetic radiation from infrared to near-ultraviolet wavelengths. In the context of light bulbs, “full spectrum” and “daylight” differ in terms of color temperature and CRI (color rendering index).

Beyond the context of seasonal affective disorder, various types of light and light bulbs may also come up in the context of vegetative growth, as people with indoor plants, for instance, may wonder how to best support plant growth while maximizing energy efficiency or using sustainable energy sources. In this context, learning more about how plants grow under red, blue, and green light may be useful.

Do full spectrum lights affect sleep?

By mimicking natural light, full spectrum lights may be used to help individuals regulate their circadian rhythm to address sleep problems and have more energy during the day. However, using too much light when trying to sleep can further disrupt sleep, so the effects can depend on the individual and how the light is used.

Do full spectrum lights help with vitamin D?

In order for a light source to help with vitamin D, it needs to contain UVB light, which is necessary for producing vitamin D. Many full spectrum light bulbs do not contain UVB light, so it can be important to research various products and light sources to find the best option for your particular needs. Spending time in the sun is often the primary way to help with vitamin D.

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