Light Therapy

Light therapy can be used as part of Wake and Light Therapy or used alone.

Light Therapy has been traditionally used to treat Seasonal Affective Disorder in which low mood, increased sleep and carbohydrate craving occurs during the Winter months. It is increasingly found to be effective against non-seasonal depression whether it is unipolar or bipolar disorder. It is not currently recommended by NICE to treat depression as evidence for its effectiveness is still emerging. However, there are plenty of small studies that have found light therapy to be effective for treating depression.

Your circadian rhythm is a 24-hour cycle that is part of your body’s internal clock. It runs in the background and carries out essential functions such as signalling when to go to sleep. Your internal clock can sometimes become out of sync with the sun. Bright Light Therapy can help reset your internal clock. This has been increasingly found to be useful to combat depression.

We know that a hormone called melatonin is released at night in the brain. Melatonin helps regulate our sleep patterns as well as other circadian rhythms. In some people affected by depression, the time when their melatonin is released becomes disrupted. Exposure to bright light in the morning is thought to suppress melatonin release. Light Therapy is grounded by the thought that resetting release of melatonin and circadian rhythms can help relieve depression.

Timing

The optimal time for Light Therapy varies from person to person. It is dependent on the individual’s internal clock. This can be established using Morningness-Eveningness Questionnaire (MEQ).

Based on results from the Morning Eveningness Questionnaire for your normal pattern of sleeping and waking, Light Therapy is usually prescribed between 06:45 and 09:00. The duration of Bright Light Therapy usually lasts for 30 minutes.

Dose

A dose of 10,000 lux of light is required.

Distance

You should sit about 1 foot (about 30 cm) from the light box (unless the manufacturer dictates otherwise). At this distance, you should be able to comfortably eat a meal, read a book or use a laptop. You should not stare into the light. Equally you should not keep your head down too far. You should maintain this distance from the light throughout the prescribed duration.

Monitor

Keep a weekly record of your symptoms to determine if you are improving. For example, complete the “PHQ-9” questionnaire which is widely available by searching.

The best summary of what you need to look for in getting a light box is from The Centre of Environmental Therapeutics (for which I am a scientific adviser). Their advice is that a light box needs:

1. To emit 10,000 lux at the required distance (usually when you are sitting 1 foot (30cm) away. (However, follow the manufacturer’s instructions for a particular light as some may be 20cm.)
2. It should have a smooth diffusing screen that filters out ultra-violet radiation (UVR). They do not advise a full spectrum light or blue enhanced light as these have no added therapeutic benefit and may be unpleasant.
3. Ideally, it should be possible to project the light source downwards i.e., slightly above the line of sight, but this is not crucial.
4. It is probably easier to use a full-size box. Compact boxes are only helpful if you are travelling.

In the summer months, it is just as helpful to go for a walk or have breakfast in the sun so long as you optimize the timing using the Morningness Eveningness Questionnaire described above.

Suitable lights include:

Lumie Brazil Light Lux used at 30cm distance. These are easy to obtain from the UK for £150. Lumie Vitamin L is more compact but for 10,000 Lux has to be used at 20cm and only suitable for travelling.

Northern Light Technologies. These are sold via the Center for Environmental Therapeutics for $180 plus carriage or direct from Canada.

Carex Day Light Classic Plus. This is sometimes available in the UK at about £250 but one usually has to import them from USA or Canada.

There are cheaper or smaller ones if you search “SAD Lights” but ensure they are 10,000 Lux and check the distance they have to be used at.

If you have bipolar disorder, then there is a slight risk of switching to mania. There needs to be a plan in place if this does occur. If you are suffering from rapid cycling which is occurring daily, then light therapy is not suitable.

Light therapy is similarly unsuitable if you have severe eye disease, traumatic injury affecting both eyes, or if you are taking photo-sensitising medication that commonly causes burns with bright light.

If you are currently working a night-shift you would need to return to a normal sleep pattern before starting the program.

If you have a chronic depression that is linked more to your personality, then light therapy may not be any benefit.

There are no known major side effects from Light Therapy. It can be used in conjunction with anti-depressant medication and other psychological therapies. Side effects are generally uncommon but include decreased sleep, dry mouth, nausea, headache, weakness and fatigue. These symptoms are transitory and can usually be managed by reducing the duration of the light therapy from 30 to 15 minutes or adjusting the distance from the light box.

Further details

Please contact me through my [email protected] if you’d like an assessment for Light Therapy.