If you want light therapy to be at its most effective there are a number of factors you need to consider, these include:
How bright is the light?
The brightness, or intensity, of a light box is measured in lux. For SAD lights the typical recommendation is to use a 10,000 lux light box at a distance of 16 to 24 inches (41 to 61 centimetres) from your face. Brighter boxes will require less usage time each day compared to dimmer boxes.
How much time do you have?
Try and be practical about how much time you can allocate per day to using any SAD light you purchase. You will need to use it every day to see results. If you lead a busy life it might be worth spending a little more to get a quicker treatment. However if you have time on your hands, there is no need to spend more as slower treatments can be just as effective.
With a 10,000 lux SAD light you will typically use it for around 20 to 30 minutes each day. A lower intensity box will require longer sessions.
As a general rule of thumb:
LUX Length of Session 10,000 20 to 30 minutes 8,000 45 to 60 minutes 2,500 1 to 2 hours
How much UV light does it release?
Essentially you want a SAD light that emits as little UV light as possible. Light boxes used to treat sad should be designed to filter out most or all UV light. If you have any safety questions, contact the manufacturer.
If you have eye problems such as glaucoma, cataracts or eye damage from diabetes ask your doctor for advice on choosing a SAD light.
Is the light specifically to treat SAD?
Some light therapy lamps are designed for skin disorders and not SAD. These lamps emit UV light mainly and will not only be ineffective when trying to treat SAD but could also damage your eyes if used incorrectly. Make sure any light you buy is specifically designed to treat SAD.
Is the SAD light convenient to use?
By this I mean can you put it in the right location? Think about where you want to put it and what you might be doing during your light therapy. Check the instructions to make sure you can place at the proper distance if you want to use it whilst you eat breakfast, read in bed, work at your computer, etc.
SAD lights now come in all shapes and sizes. Some are like upright lamps, some are small and rectangular. Make sure the one you choose will be convenient to use.
A full spectrum light covers all wavelengths from infrared to near-ultraviolet. Sunlight is full spectrum. You don’t need a SAD light that offers full spectrum light. Research has been conducted by the National Lighting Product Information Programme that shows no real benefits to full spectrum light.
What color should the light be?
More and more SAD lights are now being made that emit blue light. This is worth an article in its own right but essentially researchers have found that blue light at a lower intensity, can be just as effective as high intensity white light boxes.
The light given by the sun is made up of a range of colours but appears white. However this range includes colours such as red which is not at all effective in treating Seasonal Affective Disorder. Scientists have discovered that blue light, which is always within sunlight, is very beneficial to people suffering from Seasonal Affective Disorder – essentially it is the most energizing colour amongst the spectrum of colours in sunlight. Effectively very bright white light works because it contains blue light.
However in the world of light therapy blue light therapy is a relatively new innovation and as such there is much more research available to support the use of bright white light to treat SAD than there is for blue light as it has been around longer.
Also there are concerns over macular degeneration of the eyes and the use of blue light. It is probably best if you suffer from an eye disease or have a history of eye disease in your family, consult your ophthalmologist before you purchase this.
What about LED SAD Lights?
Not all therapy boxes use the same type of bulb. Traditionally, the most common type of bulb is either incandescent or fluorescent, but lately light emitting diode (LED) bulbs have become very popular. Ultimately it’s the quality of light you should worry about, and all three can be excellent
What angle does the light come from?
The special light receptors in your eye are mostly found in the top half of your visual field. These receptors are designed to tell what time of day it is by noticing the brightness of the sky, which is (obviously) above the horizon, not below. Meaning light therapy is most effect from above.
These don’t treat Seasonal Affective Disorder, but do help with a key symptom of SAD – difficulty waking in the morning. These lights help you awaken slowly by gradually increasing the intensity of light over a set period.
To choose a good wake up light/sunrise alarm clock you can follow a lot of the information provided when it comes to choosing a SAD light.
However with regards to the strength of the light dawn simulators use incremental amounts of light, far lower than 10,000 lux. For example some start at one thousandth of a lux and increase to 300 lux.