Blue light therapy for skin, sleep, and depression

Yael Cooperman, MD - Contributor Avatar

Reviewed by Yael Cooperman, MD, Ro, 

Written by Hope Chang, PharmD 

Yael Cooperman, MD - Contributor Avatar

Reviewed by Yael Cooperman, MD, Ro, 

Written by Hope Chang, PharmD 

last updated: Sep 21, 2021

4 min read

Light is great. Lamps and flashlights help us see in the dark, while light from the sun is harnessed into energy that gives organisms life. 

Certain types of light (like blue light) are also used to treat medical and skin conditions, including depression, psoriasis, and sleep issues. Let’s take a closer look at what blue therapy is used for––and if it actually works. 


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What is blue light therapy?

Phototherapy is a type of medical treatment that uses a light-emitting diode to help with different conditions, especially those affecting the skin (Rathod, 2021). 

Medical providers utilize what’s called an activating agent, which optimizes your body’s response to light therapy. This is called photodynamic therapy, or PDT for short (Raizada, 2021). 

Each color is made of unique wavelengths of light, which affects the type of treatment it can be used for. Blue light has wavelengths in the 400 nanometers (nm) range, while red has longer wavelengths in the 600 nm range. 

To treat skin conditions, light with longer wavelengths penetrates deeper. That’s why blue is helpful for treating thinner skin lesions, for example, while red light therapy is needed to treat thicker ones (Raizada, 2021). 

What is blue light therapy used for––and does it really work?

Blue light therapy is used for certain skin conditions and mental health issues. Effective for some health problems, research is lacking on whether blue light is helpful for others. 

Some conditions can be treated at home, while others require working with a healthcare professional. Here are the main uses of blue light therapy and the science behind each.

Actinic keratosis 

Actinic keratosis (AK) is a skin condition caused by sun damage. With AK, rough, scaly patches start to show up on areas of the body that are often exposed to the sun. AKs are precancerous lesions that may develop into skin cancer over time (Marques, 2021).

To treat AK, an FDA-approved treatment of blue light combined with an activating agent called aminolevulinic acid (ALA) is used (Sun Pharmaceutical Industries, 2020). In one clinical trial, participants applied this solution to AK lesions for 14–18 hours followed by blue light therapy. After 16 weeks, 85% of study participants reported their AK lesions had cleared up (Jeffes, 2001). 

Dermatologists recommend using ALA with blue light for AK in certain individuals (Eisen, 2021). Light treatment is typically done once in a dermatology office and can be repeated eight weeks later if needed.


Psoriasis is another skin condition where blue light therapy may be useful. Psoriasis is marked by scaly lesions that crop up when skin cells grow and multiply too quickly. 

Since blue light therapy can slow down cell growth, scientists explored if it could treat psoriatic lesions. Small studies show promising results for using blue light therapy to treat psoriasis, yet experts haven’t found enough evidence to prove that the benefits outweigh the risks (Kleinpenning, 2012; Elmets, 2019). 


Scientists have also looked into blue light therapy for acne, also called acne vulgaris. This treatment involves a hand-held light source you can use at home. The idea is that blue light kills the bacteria that causes acne, making it a potential alternative to medication and creams known to cause side effects (Gold, 2011).

In one small study, participants with mild to moderate acne had four blue light treatment sessions over two days. Significant improvements in blemish size and redness of acne lesions were seen after being treated with blue light (Gold, 2011). Other studies yielded similar results.

While the treatment shows promise, it’s not yet recommended as larger studies over a longer period of time are needed to verify it works (Scott, 2019; Zaenglen, 2016). 

Seasonal depression

Light therapy is a first-line treatment option for seasonal affective disorder (SAD). SAD is a type of depression that typically occurs during the fall and winter when days are shorter and there is less sunlight (Munir, 2021).

The benefit of light therapy for SAD is it’s a home-based treatment. There are many different options for therapy lamps including blue, red, and white light.

Blue light therapy treatments are popular since it naturally comes from the morning sun and is proven to boost vitamin D levels (Munir, 2021). One study found that blue light therapy improved SAD symptoms more than red light therapy (Glickman, 2006). 

Alternatively, there doesn’t appear to be a significant difference in results between blue and white light therapy, as both work well for SAD (Anderson, 2016; Gordijn, 2012).

Sleep disturbances

If you’ve ever struggled with insomnia, you might suspect blue light is a culprit. Electronic devices like cell phones, tablets, and computers all emit blue light, which may affect sleep quality. 

If you have trouble sleeping, experts recommend turning off devices at night or using blue light-blocking glasses two hours before bedtime (Shechter, 2018). While blue light before bed can disrupt sleep, it can be useful during other times of the day. 

Blue light early in the day may improve sleep regulation in people who have had concussions, according to one study. After a concussion, people may experience new or worsening sleep problems. This can include sleepiness during the day and difficulty falling or staying asleep at night (Raikes, 2021).

Research also suggests that using blue light therapy for 30 minutes in the morning may improve daytime sleepiness (Raikes, 2021). 

Does blue light therapy have side effects? 

Depending on your condition, there may be some side effects from blue light therapy. 

For the treatment of skin conditions, common side effects include redness, swelling, stinging, and a burning sensation in the treated area. Sometimes people experience blistering or increased photosensitivity (more sensitive to sunlight and higher risk of sunburn) within the first week after treatment. Hyperpigmentation (dark spots) and pain are common side effects in people with psoriasis, with some people reporting pain that lasts multiple days (Elmets, 2019; Choi, 2014). Otherwise, there is typically minimal downtime with light therapy.

For those using light therapy for SAD, side effects include headache, migraines, nausea, insomnia, and vision and eye-related problems (Anderson, 2016).


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

September 21, 2021

Written by

Hope Chang, PharmD

Fact checked by

Yael Cooperman, MD

About the medical reviewer

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.