White Light Therapy: What Are Its Benefits and How It Works

White light therapy is a non-invasive treatment that uses bright, full-spectrum, non-UV light to mimic natural sunlight. It’s commonly used to help manage seasonal affective disorder (SAD), seasonal depression, sleep disturbances, and even circadian rhythm imbalances. While the exact mechanism isn’t fully understood, experts believe it works by influencing the body’s internal clock and regulating melatonin and serotonin levels. Those are key hormones responsible for mood and sleep.

In this article, we’ll explore the science behind white light therapy, its potential benefits, and how you can use it.

Understanding the science: circadian rhythm

Our bodies rely on natural light cues to regulate various biological functions, from sleep and mood to hormone production and metabolism.

This internal clock, known as the circadian rhythm, follows a roughly 24-hour cycle and helps signal when it's time to be alert or wind down. Limited sun light exposure can throw this rhythm off balance, leading to insomnia and other issues.

When there is less sunlight, some people may not produce enough melatonin, a hormone in the brain involved with sleep, or serotonin, another hormone that manages mood, appetite, and sleep.

One way to simulate natural daylight is through white light therapy. This technology can offer a convenient way to reset the circadian clock, promote wakefulness in the morning, and support a more stable sleep-wake cycle.

The benefits of white light therapy

White light therapy offers promising benefits for mental well-being.

While most commonly associated with the management of SAD and other types of depression, it has also shown potential in improving sleep quality and mood disorders, as well as enhancing cognitive function.

Here's a closer look at what the research says.

Addressing symptoms of seasonal affective disorder (SAD)

SAD is a type of depression that typically arises during the darker winter months due to reduced sunlight exposure. Symptoms include fatigue, low mood, and sleep disorders.

White light therapy, or bright light therapy (BLT), has been used for over 30 years to treat SAD. Studies found that people who received BLT (at least 1,000 lux) experienced less depression and were more likely to feel better than those who got dim light or fake treatments.

It’s important to mention that most studies tend to have small sample sizes and differences in quality. While the results are promising, more high-quality research is needed to understand BLT’s full potential for treating SAD.

Addressing symptoms of depression

Apart from SAD treatment, white light therapy has also been explored for various forms of depression.

Research shows that BLT can work well when used for 2–5 weeks. However, more research is needed to figure out the best timing, brightness, and length of each session.

Other studies have found that bright white light helped with depression in older adults, although additional types of light therapy were also used during the process.

Regardless of the limitations in these studies, BLT appears to be a potential solution for addressing depression symptoms.

Other improvements

Some research also suggests white light therapy may benefit sleep patterns and mood.

A review of several studies found that light therapy can help people with insomnia sleep better by reducing how often they wake up during the night. Getting light in the morning helped people fall asleep and wake up earlier, while light in the evening made them stay up longer.

While these results are encouraging, the studies were quite different from each other and often involved small groups. More research is needed to determine the best way to use light therapy for various sleep disorders.

How white light therapy works: what to expect

White light therapy is simple to use, but there are a few key steps to consider to make it more effective.

The light box setup

Sit near a certified lightbox that delivers 10,000 lux of brightness. Place it about 16 to 24 inches from your face. You don’t need to stare directly into the light — just keep your eyes open while the light enters from the side.

The benefits come from the light box emitted rays hitting your eyes, not your skin.

Optimal timing and routine

Dr Tracy Marks, a psychiatrist and corporate mental health speaker, made a video in which she discusses the benefits of white light therapy in the morning.

Using the lightbox within an hour of waking helps reset your body clock. “If you use light too late in the day, it can actually push back your sleep to where you have trouble going to sleep in the early evenings,” says the specialist.

She recommends sessions between 15–45 minutes — a shorter duration for waking up and a longer one for treating more serious issues like depression symptoms. They should typically subside within a few days.

As always, track your well-being and communicate with your doctor to adjust the treatment based on your needs.

Important considerations

White light therapy is generally safe, but it’s always best to talk to a healthcare professional before starting.

This is especially important if you have any pre-existing conditions or take medications. A doctor can help determine if light therapy is right for you and guide you on how to use it safely.

You should definitely consult a physician if you have:

• A history of skin cancer or a skin sensitivity condition (like lupus or rosacea)
• Eye conditions such as glaucoma, cataracts, or retinal problems
• Bipolar disorder or manic depression, as light therapy can sometimes trigger mania
• Certain medications that increase light sensitivity, including certain antibiotics, antihistamines, or psychiatric drugs

Managing potential side effects

Most people tolerate white light therapy well, but some may experience mild side effects when starting out. These can include headaches, eye strain, irritability, or slight nausea if the light is too intense or used for too long.

To minimize discomfort:

• Start with shorter sessions and gradually increase the duration as your body adjusts
• Use the correct distance and angle to avoid direct glare into your eyes
• Avoid evening sessions, which may interfere with sleep or cause restlessness
• Take breaks if you notice eye fatigue or tension
• Adjust brightness or timing based on how you feel during and after sessions

These effects usually go away on their own. However, if symptoms persist or worsen, you may need additional measures. Keep track of how you feel and how long you use light therapy daily. Communicate with your doctor so that treatment can be adjusted as needed.

Safety of light therapy

Most lightboxes are designed to emit broad-spectrum light without UV rays, so there’s no risk of sunburn or skin damage. Unlike tanning beds, therapeutic lightboxes filter out ultraviolet light entirely.

Because of this, white light therapy doesn’t carry the same risks as sun exposure and typically doesn’t interact with medications the way sunlight might. However, if you’re taking light-sensitive medications, it’s smart to double-check with your doctor just to be safe.

When used correctly, light therapy may offer a low-risk approach to supporting mood, sleep, and overall well-being.

Beyond the basics: additional insights

Once you understand how white light therapy works, you might wonder how it compares to other treatments or how to make the most of it in your daily life.

Here are a few deeper insights to help you take a more informed approach.

Comparing white light to other light therapies

White light therapy differs from other types, such as red, near-infrared, blue light therapy.

For example, white light works through visual pathways and targets mood, sleep, and the circadian rhythm. On the other hand, red light therapy is often used for skin concerns and health, pain relief, tissue repair and reduce inflammation. Red and near-infrared wavelengths penetrate deeper into the body but do not stimulate the same brain pathways that affect mood and alertness.

Each therapy has its purpose. The one you choose will depend on your goals.

Understanding light illuminance (lux)

In light therapy, illuminance is measured in lux — a unit that reflects how much light reaches your eyes.

For mood-related conditions like depression, the standard recommendation is 10,000 lux for about 20–30 minutes. For milder cases or maintenance, lower intensities (2,500–5,000 lux) may still be helpful.

Always follow your lightbox’s guidelines and tailor the setup to your sensitivity and needs.

Choosing the right lightbox

Not all lightboxes are created equal. When shopping for one, look for these key features:

• UV-free, full-spectrum white light
• Brightness of up to 10,000 lux at a comfortable distance
• Large screen size for even exposure
• Certifications from regulative authorities
• Adjustable settings for brightness and timer control

Avoid products that resemble tanning lamps or emit UV light, as these might not be suitable for therapeutic use.

Integration into a holistic wellness approach

White light therapy works best as part of a broader self-care routine. You can enhance results by combining it with other healthy habits:

• Regular exercise to boost mood and energy levels
• A balanced diet rich in nutrients that support brain health
• Mindfulness or relaxation techniques to reduce stress and the presence of sleep disorders

White light therapy: final thoughts

White light therapy offers a potentially safe way to improve mood and sleep and support overall well-being.

When used properly, at the right time of day, with the correct light intensity, and as part of a consistent routine, it can be a powerful addition to your daily health habits.

That said, professional guidance is key. If you have underlying health conditions or take medications that increase sensitivity to light, it’s important to consult a healthcare provider before starting.

As our understanding of light and its effects on the body continues to grow, therapies like this remind us how closely our well-being is tied to the rhythms of nature. Whether you're looking to lift your mood, improve your sleep, or feel more energized, white light therapy may be a bright idea worth exploring.