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Light therapy

The Light, the eye and the human rhythm

 

We know today that light acts as a natural clock for many physiological processes. Bright light travels in the form of electric impulses via the eyes and the optical nerves to the "inner clock" of our brain.

 

The "inner clock" processes the information about light and darkness and instructs other parts of the brain to rhythmically distribute chemical messengers such as the "sleeping hormone" melatonin and the neurotransmitters serotonin and norepinephrine which are known as the "good mood makers".

 

In periods of darkness melatonin is produced and in periods of sufficient light, the body ceases to produce it.

 

The therapy only takes between 30 minutes and two hours, depending on the power of the lamps used. The lamps usually consist of fluorescent tubes which convey a luminous intensity of either 2,500, 5,000 or 10,000 lux.

 

The UV part of the light is filtered out in view of the possible risks to the skin and eyes. The infra-red rays are also eliminated as a precaution against the risk of contracting cataracts.

 

During the therapy the patients sit between half and one metre away from the lamp. They should keep their eyes open and they can simultaneously read, work, watch television or pedal away on their training bike.

 

There is some speculation as to whether the success of the light therapy can be accounted for as a placebo effect, that is a positive effect which is based purely on faith in the therapy.

 

However, most patients really do experience a definite, positive effect; this could be seen in tests using a less bright light where the results of the therapy could rarely be called successful.