Light Therapy For Depression

Can you treat depression effectively using light therapy?

Light therapy is a natural treatment where you are exposed to artificial light, in an attempt to replicate the effects of natural sunlight. We know that natural sunlight is great for our well-being – the use of sunlight for medicinal purposes has a long and interesting past, going back to very old cultures and civilizations, where it was known as heliotherapy. If you can’t be in the sun, light therapy is considered “the next best thing”.¹ It may be particularly helpful in the winter when days are short and there isn’t a lot of natural light. That’s why it is often used for people who suffer from seasonal depression, also known as seasonal affective disorder (SAD). There is also some evidence that it may help with other forms of depression too.² 

Depression is when you feel persistently sad for weeks or months. It can affect people in different ways and can range from mild to severe (where it may even lead to feeling suicidal). For some, it manifests as feelings of unhappiness and hopelessness, while for others it may involve losing interest in the things they enjoy or feeling very tearful. Some people experience physical symptoms such as feeling constantly tired or sleeping badly and having no appetite.³ Depression can be caused by a number of things, like the loss of a family member – or sometimes there is no obvious trigger at all. But for around 2 million people in the UK and 12 million across northern Europe, seasonal changes and lack of sunlight exposure may be the reason for their depression.³ Seasonal Affective Disorder (SAD) is a cyclical mood disorder that typically occurs during the autumn and winter seasons and gradually improves in the subsequent spring and summer seasons.⁴

How light therapy works 

Light therapy is usually performed early in the morning using a device known as a light box, which emits bright light similar to natural sunlight. Using the right frequencies and exposures (10,000 lux in the morning for at least 30 minutes a day throughout the whole of winter) can increase serotonin (the “feel good” hormone) and norepinephrine levels, the chemicals in your brain that play a role in mood regulation.

Studies have suggested that bright light therapy might work by affecting your circadian rhythm (your body’s natural 24-hour cycle) and serotonin uptake in the brain. We don’t know exactly what causes seasonal depression but a current theory known as the “phase-shift-hypothesis” suggests there is an optimal way for your sleep-wake cycle and your internal circadian rhythm to align. As the length of the day shortens in the winter, your circadian rhythm begins to shift later in terms of clock time, and therefore no longer aligns with your sleep-wake cycle. It is this delay or misalignment that is thought to bring about depressive symptoms. A concentrated amount of bright light in the morning is thought to generate a circadian phase advance, which is thought to reset, or correct, the discordance between sleep and circadian phase, and thereby improve depressive symptoms. 

Types of light therapy

Most research on light therapy for depression is on being exposed to bright white light which is called Bright Light Therapy. However, there are other types of light therapy that may also be effective in treating depression. Dawn Simulation is a technique that involves timing lights in the bedroom to come on gradually, over a period of 30 minutes to 2 hours, before you wake up in the morning – this is thought to simulate dawn. These lights are often called wake-up lights, sunrise alarm clocks or natural light alarm clocks. Dawn simulation generally uses light sources that range in illuminance from 100 to 300 lux, while bright light boxes are usually in the 10,000-lux range. Because the entire treatment is complete before you even wake up, dawn simulation may be a more convenient alternative to bright light therapy, where almost 20% of people discontinue their treatment due to inconvenience. Some research suggests that dawn simulation may be similar or even more efficient in treating seasonal depression than bright light therapy.^5,6 

Blue light therapy is another type of light therapy that is sometimes used to treat depression. One study found that the use of blue-light treatment is equally effective as bright white-light treatment.⁷ Research has been generally positive, however, current meta-analyses suggest that blue-light therapy is still an unproven therapy so we’re not sure how effective it really is.⁸ Much like with white light therapy, blue light therapy is thought to help regulate emotional responses in the brain, by altering the circadian rhythm, suppressing melatonin secretion and modulating serotonin levels.⁸ 

What does the research say?

After light therapy sessions, improvements have been found in alertness, mood, energy, attention, concentration, happiness, and other markers of depression.⁹ 

Light therapy is an accepted treatment option for depression, with several recommendations and guidelines for the treatment of depression advocating light therapy as an option (for example the National Institute for Mental Health). However, methodological limitations of research looking into its efficacy mean that the evidence for light therapy being an effective treatment can be questioned.¹⁰ While many studies report positive effects of light therapy, when followed up over time it becomes clear that the effect light therapy has on depression is only temporary. While the research evidence for the effects on seasonal depression is favourable, new well-designed studies with larger sample sizes and high quality are needed to confirm the efficiency of light therapy in treating non-seasonal depression.¹¹ 

How does light therapy compare to other treatments for depression?

Bright light therapy has been shown to have superior effects compared to other interventions including antidepressant medication and cognitive behavioural therapy based on depression scores.⁴ Given this evidence, light therapy is of great interest as an alternative to pharmacological treatment.¹⁰ Research has also found that using a lightbox in conjunction with other therapies yields better management of symptoms.

While many people find some depression or other condition relief when using light therapy on its own, it’s not a cure for the condition and is unlikely to completely relieve all symptoms. That’s why light therapy is typically used in combination with other types of treatment and healing techniques such as talk therapy or cognitive behavioural therapy, and medication, and is considered a way to reduce symptoms and help you cope. Light therapy is likely to be most effective when complimented with other lifestyle changes known to be beneficial for our wellbeing such as getting outside, keeping active, eating healthily and seeing friends and family.

Is light therapy safe?

Light therapy is generally very safe. Most people have minimal side effects, if any at all. It has fewer side effects than other depression treatments and does not negatively impact any other treatment people may be undergoing at the same time.⁹ If you have an eye condition or light-sensitive skin this treatment is likely not right for you. 

Some people have reported side effects when undergoing light therapy. These include irritability, headaches, eye strain, sleep disturbances, nausea and insomnia. These adverse impacts are usually minimal and go away when the device is turned off or after a few days.

Although it is considered to be relatively safe, it is still recommended to check with your GP or mental health provider if light therapy would be right for you. And always consult a doctor before stopping other treatments. 

How should you use light therapy?

Light therapy is easy to use. All you need is a light therapy box or lamp and somewhere to plug it in. You then sit close enough for your eyes and skin to absorb the light for an allotted amount of time. It is important to choose an appropriate light therapy unit (you could ask your GP for advice) and to implement a standardised regimen that has been well-tested. Most studies indicate that early morning treatment (before 8 am) is optimal.

It is important to receive 10,000 lux of exposure, and at the proper distance (following the manufacturer’s recommendations), which can be achieved with the better light boxes over 30 minutes of exposure. It is best not to use light therapy for more than 60 minutes a day.¹¹ You also want to make sure that you don't look directly into the device during the whole session as that could damage your eyes. Instead, the intention is that your eyes pick up the light indirectly. You can read or have breakfast as you use the light. 

It is also important that light therapy is used consistently on a day-to-day basis, as the therapeutic effects wane quickly if it is not used regularly. As it has a rapid therapeutic effect, light therapy is usually implemented as symptoms begin to emerge, rather than as a preventive treatment.¹² Treatment is typically continued through the autumn and winter period and discontinued at the time of natural remission of depressive symptoms in the spring and summer.

Summary

Light therapy is a promising treatment option, particularly for depressive symptoms that show seasonal variation – so it may help get people through the gloominess of autumn and winter months. It shows some promise to be effective for patients with non-seasonal depression as well and can be a helpful additional therapeutic intervention for depression.¹³ It has minimal side effects and is accessible as all you need is the light itself (a cost that is often covered by health insurance). If you suffer from seasonal depression light therapy is definitely something that is worth considering.