Light Boxes for Seasonal Affective Disorder
How Blue Light Therapy can Alleviate Seasonal Depression
Nov 9, 2009
According the NHS’ online information, “seasonal affective disorder,” one in 50 people suffer from SAD and it affects twice as many women as men. Although it can affect anyone of any age, it affects mostly people between 18 and 30 years of age. A milder form, known as “winter blues” (or sub-syndromal SAD) is experienced by one in eight people in the UK.
Symptoms of SAD
Sufferers of SAD may experience any or all of the following symptoms:
- fatigue
- difficulty in concentration
- low motivation
- cravings for carbohydrates
- depression
- lowered sex drive
- disturbed sleep
The symptoms of SAD set in around early autumn and grow progressively worse as the days shorten until the winter solstice is reached. In the northern hemisphere, this will be around December and January; in the southern hemisphere, this will be around June to July. In the spring, the symptoms of SAD will ease and eventually disappear. The occurrence of SAD diminishes towards the equator.
What Causes SAD?
A BBC News’ article, “Brain Chemistry Winter Blues Link,” (BBC, Sep 2008) reports a connection between brain chemistry and SAD. Dr Jonathan Johnston, a lecturer in neuroscience at the University of Surrey studied the brain scans of 88 volunteers over three years and found that lack of daylight activated special proteins within the brain that clear out the mood lifting seratonin, causing lowered mood. An improvement in symptoms has been reported when sufferers were exposed to bright bursts of simulated daylight at around dawn.
Blue Light Box Therapy
At first, it was thought that mere light exposure to the eye helped lift mood, but Professor Alan Bird, an eye specialist at the Moorfields Eye Hospital, discovered special light receptor cells in the back of the retina reacted with blue light, causing the pineal gland to produce less melatonin, a sleep hormone. Results have shown a significant reduction in the production of the sleep hormone if subjects sat in front of a light box for half an hour in the morning, helping to promote alertness.
Research into SAD
These findings would suggest that light therapy might help alleviate the symptoms of SAD. But knowing how much is required and when to administer it is equally important.
The American Psychological Association’s research article, “Light Therapy for Seasonal Affective Disorder: A Review of Efficacy,” (Michael Terman et al, March 1989) tells how 332 volunteers were given light therapy treatment over five years. The results yielded the following observations (using the Hamilton Rating scale for depression):
- Bursts of simulated daylight measuring 2,500lux in intensity for around two hours per day over the period of a week, resulted in significantly improved symptoms.
- When light was administered in the early morning, patients reported 50% reduction in symptoms.
- When light was administered in the early evening, the figure lowered to 38%.
- When light was administered at midday, this was 32%.
- Administering of dim light was less effective.
- Dual light administration (both morning and evening) showed no added benefits to morning exposure alone.
Seasonal Affective Disorder Lamps
It would seem from research into seasonal affective disorder that using light therapy is an effective treatment for this condition as well as jet lag and for night shift working. Not only does it stop the brain from clearing the mood lifting hormone seratonin, it also lowers the amount of the sleep hormone melatotin, helping to lift mood and promote wakefulness. SAD lamps have also been found to be beneficial for shift working, jet lag and insomnia. Early morning treatment would seem to be more effective than exposure during any other time of the day.
References:
NHS “Seasonal Affective Disorder” (NHS, 2008)
BBC News “Brain Chemistry Winter Blues Link” (BBC, Sep 2008)
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