SEASONAL AFFECTIVE DISORDER

Seasonal Affective Disorder(SAD) is a type of winter depression which affects an estimated half a million people every winter between September and April - in particular during December, January and February. It is caused by a biochemical imbalance in the hypothalamus due to the shortening of daylight hours and the lack of sunlight in winter. For many people SAD is a seriously disabling illness, preventing them from functioning normally without continuous medical treatment. For others, it is a mild but debilitating condition, causing discomfort but not severe suffering, which is called sub-syndromal SAD, or "winter blues". There is also a rare reverse form of SAD, known as summer SAD, where symptoms occur each summer and remit in winter.

Symptoms

The symptoms of SAD usually recur regularly each winter, starting between September and November and continuing until March or April, and a diagnosis can be made after three or more consecutive winters of symptoms, which include a number of the following:

• sleep problems; usually a desire to oversleep and difficulty staying awake but, in some cases, disturbed sleep and early morning wakening
• lethargy; a feeling of fatigue and inability to carry out normal routine
• overeating; craving for carbohydrates and sweet foods, usually resulting in weight gain
• depression; feelings of misery, guilt and loss of self-esteem, sometimes hopelessness and despair, sometimes apathy and loss of feelings
• social problems; irritability and desire to avoid social contact
• anxiety; tension and inability to tolerate stress
• loss of libido; decreased interest in sex and physical contact
• mood changes; in some sufferers, extremes of mood and short periods of hypomania (overactivity) in spring and autumn

Most sufferers show signs of a weakened immune system during the winter, and are more vulnerable to infections and other illnesses. SAD symptoms disappear in spring, either suddenly with a short period (e.g. four weeks) of hypomania or hyperactivity, or gradually, depending on the intensity of sunlight in the spring and early summer. In sub-syndromal SAD, symptoms such as tiredness, lethargy, sleep and eating problems occur, but depression and anxiety are absent or mild. In summer SAD, symptoms may be related to excessive heat rather than light, and may include irritability and lethargy rather than oversleeping and overeating.

SAD may begin at any age but the main age of onset is between 18 and 30. It occurs throughout the northern and southern hemispheres, but is extremely rare in those living within 30 degrees of the Equator, where daylight hours are long, constant, and extremely bright.

Treatment

Light therapy has been proved effective in up to 85 % of diagnosed cases. This entails exposure for up to four hours per day (an average of 1 to 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 while stationary in front of the box, reading, working, eating, knitting etc. It is not necessary to stare at the light although it has been proved to be 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 which 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 now free of VAT and start at less than £100. The Seasonal Affective Disorder Association (SADA) recommends trying before buying. Several companies offer a home trial or hire scheme, and SADA has a number of boxes for short term hire. Other fixtures now available include a light visor and a dawn simulator.

Traditional antidepressant drugs such as tricyclics are not usually helpful for SAD, because they exacerbate the sleepiness and lethargy which are symptoms of the illness. The non-sedative SSRI drugs such as paroxetine (Seroxat), sertraline (Lustral), and fluoxetine (Prozac), are effective in alleviating the depressive symptoms of SAD, and combine well with light therapy.

Other psychotropic drugs (e.g. lithium, benzodiazepines) have not proved widely useful in the treatment of SAD. Daily exposure to as much natural daylight as possible, especially at midday, should help. Psychotherapy, counselling, or any complementary therapy which helps the sufferer to relax, accept their illness, and cope with its limitations are extremely useful.