How does a SAD Light work?

If you or someone that you know has been recently diagnosed with Seasonal Affective Disorder and were advised in having light therapy treatment by a Medical Professional such as you GP then you may find yourself wondering exactly ‘How does a SAD Light work?’.

The basic idea behind how a SAD Light Therapy box works is to create a simulation of sunlight at the most convenient time for sufferers of Seasonal Affective Disorder so that the Melanopsin receptors in the eyes can trigger the required Serotonin release within the brain for natural sleep cycles and general feelings of well-being.

In order for a SAD Lamp to provide the required amount of light for this Serotonin release it needs to emit light to a minimum of 2,500 lux (Lux is the unit of intensity light is measured in).  To achieve this bright intensity of light specific SAD bulbs were created for use in SAD light units which have diffusers to make the light from the bulbs softer on the eyes and also allow for a timed treatment so that you receive enough and not too much, or too little as both can affect your sleep pattern.

More recently LED SAD lights have become more commonplace as they will emit 10,000 lux and last much longer before needing to be replaced.  The main advantage of the higher lux is that the greater intensity of light decreases treatment time, yet is just as effective as lower intensities.  This is ideal for individuals that lead busy lifestyles.

On average in order for a SAD Light treatment to work, the unit should be placed at a specific distance away in front of you, typically to either side so is in your peripheral vision and never directly.  Each type of SAD therapy light may have different required distances and treatment times depending on the exact lux they emit or the kind of light, as some have blue LED’s instead of the standard white.  Blue wavelength LED’s have been found to provide an even shorter treatment time with less intense light.

SAD Lights should be used early on in the day as it will help give you a boost for throughout the day and you will then be able to relax in the evening.  Using one later in the day after mid-afternoon will likely cause you to be alert through the night and adversely affect your sleeping pattern.

After regular use of a SAD Light over time, hopefully you will find symptoms of Seasonal Affective Disorder lessen and your circadian rhythms return to normal, providing you combine it with a healthy lifestyle and any other treatment that your medical professional has advised you to have. provides general information only and should not be regarded as a substitute for medical advice from your own doctor or healthcare provider.
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