How Light Therapy Works

Light therapy is a popular option for anyone looking to enhance their health holistically. This guide breaks down everything you need to know about light therapy treatment, including how sun lamps work, what light therapy is used to treat, how to use a SAD lamp effectively, the benefits of a SAD lamp, what to look for in a SAD lamp, and more.

Hint: Don’t feel like reading? Each section has its own “TL/DR” summary at the bottom with a list of key takeaways.

The Importance of Sunlight

While we take it for granted, sunlight is vital to our existence. The benefits of sunlight are endless.

Exposure to the sun helps our bodies produce essential vitamins and hormones such as melatonin and serotonin. These significantly impact our mental health, energy levels, and physical health.

One essential hormone the sun aids in production is melatonin. Melatonin is a crucial regulator of our sleep-wake cycles, also known as circadian rhythm. Sunlight exposure during the daytime causes our bodies to produce melatonin sooner, so we’re better able to sleep at night. Consistent sunlight exposure is necessary for synchronized melatonin production and a healthy sleep-wake schedule.

Another critical hormone sun exposure aids in is serotonin, which eventually converts to melatonin. Serotonin plays a significant role in many functions, including:

• Mood
• Appetite
• Sexual desire
• Memory
• And energy levels. 

Because of its massive role, serotonin is critical to having a healthy body and quality of life.

Because our lifestyles revolve around being indoors, we don’t get enough sunlight. The US environmental protection agency reports that Americans spend 90% of their time indoors. While artificial indoor lighting helps, it’s not nearly as beneficial to our bodies as natural sunlight.

A key area to look at when it comes to lighting is LUX. This is the measurement of how intense light is. The lighting in an office ranges from 400 to 700 LUX, while the sun produces up to 81,000 LUX in the springtime.

Another critical area to highlight is the winter months when days get shorter and our access to sunlight significantly diminishes. Most of our work schedules cause us to leave for work at sunrise and not get home until it’s dark outside, missing out on sun exposure. This lack of sun causes our bodies not to produce essential hormones and can disrupt sleep schedules. A poor sleep schedule can result in conditions such as:

•  Insomnia
• Depression
• And seasonal affective disorder.

What is Bright Light Therapy?

Bright light therapy, also called phototherapy, light exposure therapy, heliotherapy, sunshine therapy, and chromotherapy, is eye exposure to a light that mimics sunlight.

What is a Light Therapy Lamp?

A light therapy lamp is a specialized light used to treat conditions such as seasonal depression, insomnia, and jet lag. These lights produce high amounts of LUX (light intensity) to mimic sunlight to trigger biological effects effectively. They are most commonly used during fall and winter when sunlight is minimal.

How do Light THerapy Lamps Work?

Light therapy lamps trick our bodies into producing melatonin and serotonin when sun exposure is limited, especially in the fall and winter.

Morning light therapy replaces lost sunlight and can help reduce symptoms of circadian rhythm disorder. This condition occurs when insufficient serotonin and melatonin are produced in the body. Replacing lost sunlight allows us to fall asleep easier at night and have more energy and positive emotions during day time.

Types of Light Therapy Devices

• Light Box: These are the most popular types of light therapy devices. Light boxes are usually smaller and direct light upward from an angled position. Because of their compact size, they’re more suitable for tight spaces and travel. It’s important to note that these devices don’t point light from an upward angle, making them less ideal for those with severe conditions.
• Desk Lamp: This style is similar to light boxes but differs in size and angle. Desk lamp-style therapy lamps point light down from an upward position and are larger. This makes them doctor-recommended and more desirable for those with severe conditions.
• Light Visor: These are the most portable method of light therapy. Light visors look like tennis visors with LEDs attached underneath. These lights shine directly into your eyes from an upward angle.
• Dawn Simulator: These are much like light boxes but have built-in technology that gets brighter and dimmer to simulate the sun rising and setting. They usually have an alarm clock that causes the light to brighten after going off.

The History of Light Therapy

While bright light treatment has grown in popularity over the recent years, it’s nothing new. This section breaks down the key historical events and findings that led to modern sun lamp treatment.

400 BC: The importance of sunlight is first published

Hippocrates first writes about the positive effects of sunlight on mental health and mood. His writings would be paraphrased by doctors worldwide, emphasizing the adverse effects of inadequate sun exposure.

Early 1800s: First sun benefits found

Studies find sun exposure to help tuberculosis patients in psychiatric hospitals.

1890: The first Carbon Arc lamp is developed

Niels Ryberg Finsen, a Danish physicist, develops the first carbon arc lamp. This lamp emits ultraviolet (UV) radiation to treat tuberculosis.

1984: The first official definition of Seasonal Affective Disorder is published

Seasonal affective disorder, known as circadian rhythm disorder, is first scientifically described by Norman Rosenthal and other researchers. Rosenthal cites using lightboxes equipped to produce powerful light as an effective treatment method.

1990s to 2000s: More extensive studies conclude light therapy to be effective

As interest in light therapy expands, the scientific community conducts multiple studies and finds it effective in treating various illnesses. As a result, personal light therapy has become more accessible.

Today: Light therapy is in popular culture

The holistic method of light therapy is considered one of the first treatments for seasonal affective disorder and other mood and sleep disorders. Its low cost and safety make it a simple yet effective treatment method.

Does bright light therapy work?

While more research is required, many studies from the 1900s have concluded that light therapy effectively treats various circadian rhythms and mood disorders.

A 2005 study found light therapy lamps beneficial in treating many conditions. The research found exposure to these specialized lamps aided in a patient’s ability to manage sleep disorders, have regular sleep cycles, and sleep continuously through the night. It also found light therapy to ease SAD, nonseasonal depression, senile dementia, and jetlag symptoms.

Another study in 2015 found light therapy to be as effective as cognitive behavioral therapy while also improving acute depression symptoms.

To best answer “do light therapy lamps work,” we’ve highlighted critical studies on the effects of light treatment on specific conditions.

Sleep Disorders

In a systematic review and meta-analysis, researchers collected and analyzed 53 studies with 1,154 participants. They found bright light therapy for sleep disorders effective in treating:

• General sleep issues
• Circadian rhythm disorders
• Insomnia
• And Alzheimer’s.

Seasonal Affective Disorder

A meta-analysis involving 14 research centers and 332 patients over five years found 2,500 LUX light therapy for a minimum of two hours per day to significantly reduce symptoms of seasonal affective disorder.

The analysis also concluded that light therapy’s effectiveness for SAD increases when conducted in the morning rather than midday or evening.

Non-Seasonal Depression

A 2005 review article collected various light therapy studies on the effects of nonseasonal depression. The research case found that not only is bright light therapy for depression an effective treatment, but it’s more effective than antidepressant drugs. Light therapy could do what antidepressant drugs achieved in as little as one week compared to 4 to 16 weeks.

Twenty-seven nonseasonal MDD patients were treated with light therapy for seven days. They had a 24% benefit to light therapy over dim light. An additional study treated 28 unmedicated patients with 3,000-4,000 LUX ceiling lamps, resulting in a 50% improvement in their depression rating scale in 17 of those 28 cases.

Twenty-nine inpatients with nonseasonal recurrent MDD in a blinded trial experienced a 64.1% increase in rating scores after three weeks of two-hour 5,000 LUX morning light treatment. These results were coherent to those given 150 mg of imipramine per day or a combination of light with imipramine.

Another study treated 29 inpatients with chronic MDD with light therapy for two years. Patients experienced a 50% remission rate compared to a control group given low-density negative air ionization.

Senile Dementia

Sleep disturbances are a typical symptom and result of dementia. Because light therapy effectively regulates sleep, its thought to be an effective aid in reducing dementia symptoms.

Light therapy studies on Alzheimer’s patients have concluded it to be an effective treatment for treating the condition’s associated sleep disturbances. However, this treatment is only effective for patients with shorter disease duration and in a mild-moderate stage.

A three-week study treated 37 institutionalized patients aged 70 to 93 with light therapy. The patients involved experienced improvement in both sleep and cognitive abilities.

Jet Lag

Traveling to different time zones can cause our circadian rhythm to be thrown off. This typically results in the following:

• Increased daytime sleepiness
• Poor sleep quality & duration
• And decreased performance.

One study exposed subjects to three days of light therapy and found it effective in creating an advance or delay in sleep-wake cycles. This “phase shift” gave subjects an average sleep-wake cycle shift of about 2.1 days. Using a light therapy lamp for jet lag tricks our circadian rhythm into adjusting to the new time zone.

Shift Work Adjustment

Any job that causes an inconsistent sleep-wake schedule can create havoc on one’s circadian rhythm and cause sleep disturbances, low energy, and mental fatigue.

The use of light therapy offers a solution to shift work adjustment. One study highlighted how a therapy lamp can be used in a strategy called “circadian resetting.” This method involves continually using light therapy before one’s bedtime.

Please note this method can worsen sleep-wake symptoms. It’s best to speak to a medical professional before attempting.

The Pros and Cons of Light Therapy Lamps

Understanding the pros and cons of any holistic health practice is essential. Below, we highlight the many benefits of therapy lights and the cons to help you decide if this treatment is proper for you.

Who Should Use Bright Light Therapy?

Light therapy offers a natural and holistic treatment for a variety of conditions. A few generalized signs and symptoms you might benefit from light therapy include:

• Feeling depressed most of the year or in the fall/winter months
• Feeling tired during the day, even when you’ve slept enough
• Inconsistent sleep schedules or sleeping too much/little

These signs can be a signal of underlying conditions. It’s best to consult your doctor so they can pinpoint the specific cause. Below, we highlight specific conditions light therapy has been found to treat and the symptoms typically associated.

Seasonal Affective Disorder (SAD)

Often called seasonal depression or the winter blues, SAD symptoms include feeling depressed most of the day, every day, in addition to:

• Low energy levels
• Sleep difficulties or oversleeping
• Problems concentrating
• Weight gain
• And feelings of hopelessness

SAD symptoms typically start at the beginning of the fall season and continue into the winter months. People living in northern areas where the sun is minimal during cold months are more susceptible to seasonal affective disorder.

Depression

While sharing similar symptoms of seasonal affective disorder, depression is not based on the time of year and persists year-round. Symptoms of depression include: 

• Loss of interest in enjoyable activities
• Sleep problems of oversleeping
• Low energy levels
• Challenges with concentrating, thinking, decision-making, or remembering things
• Weight gain or loss

Sleep Disorders

Light therapy can help with sleep-related conditions such as insomnia and circadian rhythm disorder. Symptoms of sleep disorders include:

• Daytime exhaustion
• Difficulties falling asleep or staying asleep during the nighttime
• And an irregular sleep-wake cycle

Jet Lag

Jet lag is a temporary sleep disorder that happens when you’ve traveled across different time zones for a short period. Jet lag symptoms include:

• Disturbed sleep
• Fatigue during the day
• Problems concentrating
• And mood changes

Light therapy resets your sleep-wake cycle by tricking your body into thinking when the sunrise occurs.

Shift Work Adjustments

Those whose job requires a shifting schedule often experience an unsynchronized sleep-wake cycle. Light therapy can help by syncing your body’s internal clock while enhancing night-shift performance.

Who Should Not Use Light Therapy

Light therapy may not be suitable for you if you experience one or more of the following conditions:

• Bipolar disorder: Light therapy can trigger a manic episode for those with bipolar disorder.
• Skin sensitivity to light: Skin conditions such as systemic lupus erythematosus can be worsened when using light therapy.
• Sunlight sensitivity from medications: Medications such as antibiotics, anti-inflammatories, or St. John’s Wort which create sun sensitivity, may be worsened by a light therapy lamp.
• Light-related eye conditions: Light therapy should be avoided if your eyes are vulnerable to light damage.

As with any treatment, it’s always best to consult your doctor to clarify if light treatment is proper for you.

How do You Use a Light Box?

Start light therapy sessions each morning after waking up to achieve the best results. Your sessions should last 20-30 minutes or as a doctor recommends. It’s always best to start sessions at the same time each day. A consistent light therapy schedule will allow your body and internal clock to adapt to light exposure simultaneously each day. Below, we go further in-depth regarding how to use a therapy lamp.

Timing: How Long Should I Use a SAD Lamp for?

When starting light therapy, use your lamp for shorter sessions and gradually increase exposure as you see fit. If treating for seasonal affective disorder, start your light treatments in the early fall when sun exposure diminishes. If your condition is more severe, start early in the year and continue therapy after dark months.

How Often Should You Use a SAD Lamp?

While this will vary from case to case, we recommend using it daily during the fall/winter. Doing so allows your body to get the needed “sunlight” to develop a healthy sleep-wake cycle when sunlight is minimal. However, those who spend most of their time indoors, even during warm months, can take advantage of the many light therapy benefits.

Where to Place Your Light Therapy Lamp?

Having the correct position is vital to light treatment. Your light should:

• Be angled at around 15 degrees
• Project over you from a downward angle
• And be centralized with your eyes, so it is shining directly into your eyes

For a 10,000 LUX lamp, consult the company’s guidelines for the best distance. The most recommended light therapy distance is between 16” and 24” from the screen. If this distance is too close for comfort, you may sit further away but sit for more extended periods. This will vary based on the make/model of your lamp.

It’s important not to stare directly into the light. This can cause eye damage. You can try reading, writing, eating, etc., during sessions. To be effective, the light needs to shine straight into your eyes.

Another critical aspect is that your light will weaken over time as its bulbs age. Thus, losing their 10,000 LUX intensity. It’s best practice to replace your lamp bulbs after two years so they stay effective.

Track Your Therapy Sessions

As with any treatment practice, it’s best to keep track of your practice. Keep track of your mood, energy, and eating habits before and after your sessions to identify effectiveness. Doing so will help determine the optimal session length, time of day, and occurrence.

Added Tip: Download our light therapy treatment tracker to keep track of your sessions and the results you’re seeing.

DOWNLOAD IN EXCEL FORMAT

DOWNLOAD IN PDF FORMAT

Adjust Treatments if Side Effects Occur

While generally safe, light therapy side effects sometimes happen. The minor side effects that occur include: 

• Headache
• Eyestrain
• Agitation or irritability
• Hyperactivity, euphoria, mania, or anxiety associated with bipolar disorder

These side effects usually subside quickly. They can be reduced by adjusting treatment timing, length, and sitting proximity. It’s always best to consult a medical professional for safety.

Another critical aspect to note is if any medications you’re on cause photosensitivity. Certain medications can cause your skin to be sensitive to light which might cause sunburn or rashes. Find a complete list of photosensitivity-causing drugs here.

Combine Light Therapy with Other Treatments

Circadian rhythm light therapy alone will not treat seasonal depression, insomnia, and more. Like other treatments, light therapy is most effective when paired with other practices. For example, a study conducted in 2015 found light therapy to be more effective when paired with cognitive behavioral therapy. Add other treatment methods such as:

• Exercise
• Outdoor activities
• Yoga
• And meditation to boost the benefits of light therapy.

How to Choose a Light Therapy Lamp

Once you’ve understood how light therapy works and what it treats, the next step is to choose the suitable therapy lamp based on your needs or preference. This section will cover the critical aspects of therapy lamps and what to look for in a SAD light.

The Difference Between Therapy Lamps and Standard Lighting

An essential topic regarding light therapy is the difference between standard lights, such as desk lamps, office lighting, and therapy lamps. The answer lies in light intensity (LUX). Therapy lamps are designed to produce enough LUX to treat conditions such as seasonal depression. While standard lighting does help our sleep-wake cycle, it doesn’t have enough LUX to help with light-related medical conditions. Certain therapy lamps produce 5-20 times more LUX than standard indoor lighting.

Standard indoor lighting commonly has warmer color temperatures. Alternatively, therapy lamps generate a cooler color temperature to mimic daylight effectively. Lighting with a color temperature that’s closer to daylight promotes awakeness. Therapy lamps also have screens that reduce glare and UV exposure to provide a safe, comfortable, and optimal treatment.

Clinical vs. Wellness-Grade Lamps

Another critical component is whether you need a clinical or wellness-grade therapy lamp. Clinical-grade lamps typically:

• Are more oversized
• Produce the recommended 10,000 LUX from 12.”
• And shine light downward from an upward position. 

On the other hand, wellness or well-being lamps are typically not ideal for treating SAD and are more compact.

What to Look for in a Therapy Lamp

Produces 10,000 LUX

One of the essential SAD light specifications is the amount of light it produces at a given surface, known as LUX. The most effective therapy lamp produces 10,000 LUX. Going higher than 10,000 LUX has no added benefits.

Large Surface Area

Lamps with a larger surface area produce more LUX from a further distance. If you have a more substantial case of SAD, a smaller therapy lamp may not produce enough LUX to see benefits. However, longer treatment sessions can suffice if a smaller light is preferred.

UV Filtration

Therapy lamps produce ultraviolet radiation, damaging your skin and eyes. For this reason, selecting a therapy lamp with a UV filter is vital.

Size

A key area to consider is where you’ll be placing your lamp. While more effective for SAD, clinical-grade lights tend to be large and unsuitable for compact spaces. Wellness lamps might require more prolonged treatment sessions but are typically better for small spaces.

Light Therapy Term Glossary

Color Temperature

A light’s color temperature is the color that it emits. It’s measured in degrees of kelvin and is commonly referred to as its “warmth” or “coolness.” This is another aspect to consider, as a warmer light will promote comfort while a cooler light will promote alertness.

Compact Fluorescent Lighting

Older lamps use compact fluorescent lighting (CFL). In a CFL bulb, ultraviolet light (UV) is emitted when an electrical current and mercury vapor react when coming into contact. The ultraviolet light, still invisible, then reacts with the phosphor coating located on the inside of the bulb. Thus, producing visible light.

LEDs have replaced CFL bulbs because of their durability, cost, and lifespan.

LED

Light-emitting diodes (LEDs) create light by directing an electrical current to a microchip that illuminates the diode. Compared to CFLs, LEDs are much more efficient at emitting light and heat and last longer.

LUX

LUX is the amount of light that reaches a particular surface from a measured distance. LUX should not be confused with a lumen which measures the amount of light a device emits. For example, the LUX of light will differ when measured from a 12” distance compared to a 23” distance. However, the lumens produced from a lamp will remain the same regardless of the distance.

Light Spectrum

Also called the electromagnetic spectrum, the light spectrum is used to explain the existing range of light. Light is measured in nanometers (nm), each having different health benefits. Red and infrared light, ranging from 660 nm to 880 nm, is commonly used for pain relief.

Regarding artificial light therapy, two types of light are used: full-spectrum and blue. A major topic is what the difference is. Blue spectrum lights use only blue light, ranging in the 415 nm range, whereas full spectrum uses a broader range of light with traces of blue light. Blue spectrum lights are considered more efficient. However, they can be harmful to the eyes, especially with medications. Full-spectrum light therapy is much safer.

Frequently Asked Questions

How Long Does it Take for Light Therapy to Work?

The effectiveness and timing of light therapy will vary on the users: 

• Sleep schedule
• Diet
• Caffeine intake
• Level of physical activity
• And any preexisting conditions. 

Light treatment can take as long as 2-3 weeks or as little as 2-3 days. For optimal results, it’s best to accompany light therapy with good health practices, including a good diet, physical activity, and healthy sleep. When light treatment is effective, you’ll experience better sleep, more energy, and enhanced mental health.

How Long Does it Take to Reset Your Circadian Rhythm?

Light therapy efficiency works because of its ability to “hack” your circadian rhythm. However, the time it takes to reset varies based on your condition. This process can take as long as a month or longer, based on what’s causing the disturbance. If it’s as simple as time zone adjustment, it can take as little as one day or even a month if it’s an extensive trip.

Can I Use Light Therapy All Day?

You may use your therapy lamp throughout the day. However, proceed with caution. Those sensitive to light might feel like they’ve consumed caffeine before bed. Overexposure to light therapy can throw off your circadian rhythm. Start with 30-minute sessions each morning and increase treatments as needed.

Can I Use a SAD Lamp at Night?

Yes, SAD lamps can be used at night. However, it’s important to proceed with caution. We only recommend using your lamp at night if you are trying to acclimate your body to being awake after the sun sets. Therapy lamps are used for those who work at night or whose work hours change frequently.

If you are trying to stay awake during the day, avoid using your lamp at night. Failure to do so can throw off your sleep-wake cycle and cause you not to be able to fall asleep during dark hours.

Does Light Therapy Help Anxiety?

Yes, bright light therapy for anxiety is effective in reducing symptoms. The secret lies in the treatment’s ability to spark melatonin production. Melatonin not only helps with sleep but also helps individuals cope with anxiety.

Can You Use a SAD Light Too Much?

Yes, however, this varies on a case-by-case basis. It’s a best practice to use light therapy in the morning when the sun rises. Users have reported not being able to sleep from using their lamps all day or later in the evening. Do not use your lamp at night, which may disrupt sleep patterns.

What are the Health Benefits of Sunlight?

Sunlight is crucial to our existence and to leading a happy and healthy life. Sunlight exposure gives us a healthy dose of vitamin D for strong bones and an immune system. Sunlight also increases your serotonin levels, aiding sleep quality, energy, and mood levels. It also helps with weight loss by shrinking fat cells.

Can Light Therapy Improve Sleep?

Light therapy improves sleep by maintaining your circadian rhythm. Light therapy mimics sunlight to trick your body into producing serotonin and melatonin, which is key to healthy sleep.

What Time Should I do Light Therapy?

When it comes to light therapy, the time of day is important. Treatments should be conducted within an hour of waking up in the morning for a minimum of 30 minutes. This mimics the sun rising and tricks your body into producing serotonin. One helpful tactic is to look up your area’s sunrise and start treatment at that time. You can do it even earlier during winter, staying with summer’s sunrise timing.