Light therapy has been shown to be effective in up to 85 per cent of diagnosed cases. That is, exposure, for up to four hours per day (average 1-2 hours) to very bright light, at least ten times the intensity of ordinary domestic lighting.
Ordinary light bulbs and fittings are not strong enough. Average domestic or office lighting emits an intensity of 200-500 lux but the minimum dose necessary to treat SAD is 2500 lux, The intensity of a bright summer day can be 100,000 lux.
Light treatment should be used daily in winter (and dull periods in summer) starting in early autumn when the first symptoms appear. It consists of sitting two to three feet away from a specially designed light box, usually on a table, allowing the light to shine directly through the eyes.
The user can carry out normal activity such as reading, working, eating and knitting while stationary in front of the box. It is not necessary to stare at the light although it has been proved safe.
Treatment is usually effective within three or four days and the effect continues provided it is used every day. Tinted lenses, or any device that blocks the light to the retina of the eye, should not be worn.
Some light boxes emit higher intensity of light, up to 10,000 lux, which can cut treatment time down to half an hour a day.
Light boxes are not available on the NHS and have to be bought from specialist retailers; they are free of VAT when used for medical purposes.
SADA recommends trying before buying; several companies offer a home trial or hire scheme.
Traditional antidepressant drugs such as tricyclics are not usually helpful for SAD as they exacerbate the sleepiness and lethargy that are symptoms of the illness. The non-sedative SSRI drugs such as sertraline (Lustral), paroxetine (Seroxat) and fluoxetine (Prozac) are effective in alleviating the depressive symptoms of SAD and combine well with light therapy.
Read NHS-accredited information on SSRIs (opens in new window)
Other psychotropic drugs e.g. lithium, benzodiazepines have not proved widely useful in the treatment of SAD.
Psychotherapy, counselling or any complementary therapy which helps the sufferer to relax, accept their illness and cope with its limitations are extremely useful.
Read NHS-accredited information on counselling (opens in new window)
Read NHS advice on healthy living (opens in new window)