Bright Light Therapy: Usage, Benefits, Risks

You might have noticed how your mood can change with the weather. 

Bright, sunny days can make you feel happier. Whereas a dark, gloomy day when you don’t see the sun might make you feel down or depressed.

Exposure to light plays a large role in our sleep patterns and even our mood. 

Bright light therapy aims to mimic the affect sunlight has on our health, which comes with several potential health benefits.

What is bright light therapy?

Bright light therapy is a form of treatment for certain mood disorder(s) and sleep disorder(s), as well as some skin conditions. 

With bright light exposure therapy, the user sits near a light therapy box that emits light for a certain amount of time each day. 

This bright light treatment aims to mimic the same kind of light as the outdoors, setting it apart from regular fluorescent lighting. 

Bright light therapy aims to mimic sunlight which impacts circadian rhythm and might improve conditions affected by lack of sunlight. This includes seasonal affective disorder (SAD), also called seasonal depression.

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How does bright light therapy work?

Light therapy lamps come in various styles, including different levels of brightness. 

You might opt for a standing lamp that can shed light on an entire room. Or you may prefer one that is table size so you can have it next to you on your desk while you work.

Light therapy lamps filter out ultraviolet (UV) rays, which can be damaging to the skin and lead to premature skin aging and skin cancer. 

Some lamps do use UV light to help treat certain skin conditions. So you should take protective measures when using those types of therapy lamps. 

Light intensity is measured in lux, with common bright light therapy intensity being 10,000 lux for 30 minutes, or a lower intensity such as 2,500 lux for 1-2 hours. 

The key to light therapy’s effectiveness is to use it consistently. 

It’s often recommended to use light therapy shortly after waking in most instances.

Light exposure from bright light therapy helps stimulate the hypothalamus, the part of the brain that regulates your circadian rhythm. 

The circadian rhythm regulates your sleep/wake cycle over 24 hours. 

Factors like light exposure have a big impact on your circadian rhythm. 

A circadian rhythm disorder can result in problems like difficulty falling asleep, waking up in the middle of the night, or waking up early and not being able to fall back asleep.

Shorter days and less exposure to natural light can lead to depressive symptoms and cause seasonal affective disorder (SAD), or seasonal depression. 

Bright light therapy is a popular and effective treatment option for people suffering from seasonal depression by helping to simulate natural light when days are shorter and darker in the winter months (in the Northern Hemisphere). 

When is bright light therapy used?

People can use bright light therapy for a variety of conditions, such as:

Seasonal affective disorder (SAD)

Otherwise called seasonal depression, seasonal affective disorder tends to impact people who live further away from the equator.

Although it can impact anyone regardless of geography. 

SAD usually causes winter depression during the fall through the spring, correlating with shorter days and less light exposure. 

Some of the symptoms of SAD are similar to those of nonseasonal depression

They include feeling depressed most of the time, losing interest in things you used to enjoy, sleep changes, unintentional weight loss, and thoughts of self-harm or suicide, among other symptoms.

Bipolar disorder

Changing seasons might impact bipolar disorder symptoms, similar to seasonal depression. 

The use of bright light therapy may help ease some of the depressive symptoms of bipolar disorder.

These symptoms include alternate periods of mania, marked by being overly upbeat, high-energy, and a sense of euphoria.

Skin conditions such as psoriasis

While most light therapy lamps filter out harmful UV rays, lamps designed to treat skin conditions use UV light. 

Psoriasis is a skin condition characterized by red, scaly patches of skin. 

It’s a long-term condition that can vary in intensity, meaning symptoms can worsen and then get better. 

Psoriasis can occur due to an overactive immune system

The type of UV rays used to treat psoriasis are UVB rays. 

UVB rays administered through a light therapy lamp can help with psoriasis by slowing the growth of skin cells.

This then helps to suppress an overactive immune system, and reduce inflammation and itchiness of the skin.

6 benefits of bright light therapy

1) It can help alleviate symptoms of seasonal depression

Seasonal depression tends to occur in the months when there aren’t as many hours of sunshine. 

For people in the Northern Hemisphere, this tends to occur during the fall through winter months. 

Bright light therapy has been used to treat seasonal depression (seasonal affective disorder, or SAD) in studies in the early 1980s. 

Despite studies on the condition, the underlying cause of SAD still isn’t completely clear. 

One hypothesis is that lack of morning sunlight can cause the brain to secrete more melatonin, a hormone that supports sleep. 

Melatonin secretion might cause depression in people who are susceptible to seasonal affective disorder. 

In studies, exposure to bright light therapy improved depression scores after only 20 minutes of exposure, reaching maximum benefits after 40 minutes. 

Part of the reason bright light therapy can help with the treatment of depression is because the light impacts serotonin production, a hormone that helps promote a happy mood. 

Bright light exposure also helps suppress melatonin secretion, which helps improve wakefulness.

2) It might help reset your circadian rhythm

Bright light therapy is often recommended for the treatment of circadian rhythm disorders. 

People with circadian rhythm disorders can have a hard time falling asleep, staying asleep, or may wake up too early in the morning. 

People who tend to want to go to sleep and wake up later than typical times are known as “phase delayed”.

For these types of people, it’s best to use light therapy in the morning. 

On the other hand, people who feel tired much earlier than typical are called “phase advanced.”

Bright light therapy might be most beneficial in the afternoon or evening for those instances. 

If you have ever worked the night shift for an extended period, you’ve likely done some damage to your natural circadian rhythm. 

Using light therapy can be helpful when transitioning from night shift back to day shift.

3) It might be helpful for those suffering from dementia

People with Alzheimer’s disease and other forms of dementia often have sleep disturbances. 

It’s estimated that people with dementia spend up to 40% of the night awake and sleep for large portions of the day. 

People who don’t sleep well during the night are more likely to display agitated behavior.

And they’re also more likely to suffer from depression due to social isolation.

Because of the potential benefits of light therapy in treating symptoms of depression and sleep disorders, it is a reasonable treatment consideration for those with dementia.

4) Bright light therapy might help improve symptoms of anxiety

Similar to depression, anxiety might result from an imbalance in serotonin levels. 

In one study, bright light therapy significantly reduced anxiety symptoms as well as depression symptoms.

And another study found a moderate improvement in anxiety symptoms. 

We need more research on bright light therapy in regards to anxiety.

But these studies show promise that it might be a helpful treatment alternative.

5) Light therapy might benefit adults with attention-deficit/hyperactivity disorder (ADHD)

Altered sleep and activity rhythms, and seasonal mood changes can worsen symptoms in people with ADHD. 

According to a study, treatment using morning light therapy could improve symptoms in adults with ADHD.

6) Using bright light lamps is convenient

Because they’ve been around for a couple of decades now, light therapy lamps have come a long way in terms of design and options. 

You can choose from various sizes, light intensities, and looks to suit your preferences and lifestyle. 

For instance, if you want to use your light therapy box at work, you can get one designed to be used on a desk. 

If you travel often, you might consider buying a travel-size therapy box for ease of transportation. 

Potential risks

While bright light therapy is generally safe, there are a few potential risks to consider.

For those using a therapy lamp that emits UV rays, such as for treating symptoms of psoriasis, there is a risk of skin and eye damage, similar to spending time outdoors in the sun.

In a study of the side effects of bright light therapy, the most common negative side effects of bright light therapy were jitteriness, nausea, and headache. 

This study emphasized that the primary outcome of bright light therapy was an improvement in symptoms.

So you should consider the benefit/risk ratio.

It’s also important to note that the Food and Drug Administration doesn’t regulate a light therapy lamp or box. 

Any claims made by these products aren’t necessarily backed by scientific proof.


Bright light therapy is a treatment involving a lamp or box that emits UV-filtered light for a specified period each day. 

Light therapy impacts serotonin and melatonin production, which impacts seasonal depression and other health conditions. 

The main potential benefits of using bright light therapy include improved mood and healthier sleep cycles. 

People using bright light treatment for skin conditions such as psoriasis use a therapy box that emits UV rays.

However, this can cause some damage to the eyes and skin if used for prolonged periods.

Bright light therapy treatment is generally safe. But, there are some potential side effects such as nausea, headaches, and jitteriness.

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  1. Campbell PD, Miller AM, Woesner ME. Bright Light Therapy: Seasonal Affective Disorder and Beyond. Einstein J Biol Med. 2017;32:E13-E25.
  2. Terman M, Terman JS. Bright light therapy: side effects and benefits across the symptom spectrum. J Clin Psychiatry. 1999.

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