What
is the physiological background of bright light therapy and depression?
Light therapy is the use of artificial or natural lighting sources
to treat various depressive and sleep disorders. This form of therapy is also
known as bright light therapy and is based on light intensity.
This intense light works to trigger a chemical reaction in the brain's pineal
gland to reduce the transformation of serotonin into the sleep hormone melatonin.
Melatonin is a hormone that is made from serotonin in the absence of light. It
is responsible for our sleep cycles, also known as circadian rhythms, and can
attribute to depression, melancholy, and lethargy.
Natural Lighting and
Depression
The effects of both bright light therapy and depression have
physical manifestations in our body. In the spring and summer months our bodies
naturally inhibit the production of melatonin due to the fact that we are exposed
to more natural lighting during the day. We perceive more light than dark. In
the fall and winter months it is the opposite. Our bodies naturally produce more
melatonin due to the shorter days causing kind of a mild hibernation for people.
Our bodies are telling us to slow down and reserve our energy for the long winter
months. The increase of melatonin causes a decreased level of serotonin as reserves
are used up. It has been proven that low levels of serotonin affect our metabolism,
mental state, and disrupt sleep patterns and the circadian clock.
Light
Box Therapy and SAD Lights
Bright light therapy works by simulating the
intensity of natural lighting, inhibiting the transformation of serotonin into
melatonin. This natural light intensity is measured in Lux, or lumens per square
meter. In order to receive the benefits of bright light therapy for seasonal affective
disorder a product must produce 10,000 lux at a certain distance. This distance
is usually between 12 and 48 inches depending on the type of product. Because
of the high intensity of light needed, natural full spectrum lighting without
UV is the most comfortable form of SAD lights for bright light
therapy causing less glare and eye strain.
Generally people use a bright
light therapy product for 15-45 minutes in the morning hours shortly after waking
when our internal circadian clock is most easily "turned back". Original mediums
of bright light therapy are light boxes. Starting light box therapy
in the evening hours can result in difficulty in going to sleep. Light box therapy
has been used very effectively since the late 1980s to alleviate the symptoms
of seasonal affective disorder (SAD). People suffering from seasonal mood disorders
or the winter blues typically notice significant mood improvement
within a week of starting light box therapy with daily morning sessions. It is
best to begin treatment with SAD lights in the early fall or as soon as the first
symptoms begin to appear and continue the treatment until spring when there is
sufficient outdoor lighting to maintain a good mood and increased energy. Bright
light therapy does not necessarily require a time commitment set aside each day.
Nor are you confined to a medium with 'light box' therapy. With the BlueMax™
desk or floor SAD lamps you can read, work on a computer, write, watch television,
or eat breakfast at the same time you receive bright light therapy. There is no
need to stare directly into the SAD lamp and the SAD light should come from above
your line of site, not at it or below it. Staring directly into an intense light
source has the potential to damage the eyes and is not needed for bright light
therapy to work.
