The secret to treating Seasonal Affective Disorder

    16 November 2020

    Without wishing to add the current sense of gloom, putting the clocks back recently did exactly that for around one in ten people in the country. They suffer from a condition that was recorded as far back as 430BC by Hippocrates and although he did not give it a name, we call it seasonal affective disorder, or SAD.

    This occurs less frequently in countries nearer to the equator where sunlight is available more regularly through the year, and typically begins during the ages of 20 to 30, with women being affected four times more frequently than men. The exact cause for SAD remains unclear but it appears to be linked to the impact of sunlight in triggering the release of chemicals such as melatonin and serotonin which affect our mood. Less sunlight during the autumn and winter months affects this balance and so can trigger depression.

    If I am considering this diagnosis, I look for evidence of cycles of definite clinical depression over at least three consecutive years as it is the pattern of someone’s behaviour over this time rather than seasons taken in isolation that is important. The symptoms of SAD usually recur regularly each Winter, starting between September and November and continuing until March or April, and there are many. These include altered sleep patterns, fatigue, a craving for sweet foods, feelings of misery, guilt and low self-esteem, a desire to avoid social contact and an inability to tolerate stress. Suicidal thoughts are seen less commonly in SAD than in other forms of depressive illness but this becomes more of a risk if the depression worsens.

    Treatment depends on the SAD severity and a pure clinical depression should be treated conventionally with anti-depressants and cognitive behavioural therapy, tailored to suit that particular individual. However, for the majority of sufferers the most effective therapy is simpler – light. Using light boxes to stimulate the natural production of serotonin does seem to help certain patients, and these are used in large numbers in Scandinavian countries, and increasingly in the UK too. These are not sunbeds, goggles are not needed and normal activity can continue around them. Ordinary light bulbs and fittings are not strong enough to help here as the average domestic or office lighting emits an intensity of 200-500 lux but the minimum dose necessary to treat SAD is 2500 lux. (Compare this to the intensity of a bright summer day which can be 100,000 lux).

    Light treatment should be used daily in winter, ideally starting in early autumn when the first symptoms appear or even before they have started. 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 towards you. If using a lightbox you can still carry out normal activity such as reading, working, eating and watching TV, and it is not necessary to stare at the light. With a powerful light source of 10,000 lux, 30 minutes a day may be all that is needed for effective treatment, but with less powerful light boxes two or three hours may be required, ideally earlier in the day rather than later. Many people start to notice an improvement in their symptoms within a few days and around 80% of people suffering from SAD report an improvement with this treatment. Speak with your GP before starting it if you have eye conditions such as macular degeneration or retinal problems, or if you take medication that can increase your sensitivity to light. Although light treatment is not available on the NHS it can be obtained from a number of reputable companies, some of whom will allow you to try before you buy to see if it works for you.

    If antidepressant drugs are required to treat SAD then the older-fashioned types such as tricyclics are not usually helpful since these may exacerbate the sleepiness and lethargy that are symptoms of the illness. The non-sedative SSRI drugs are effective in alleviating the depressive symptoms of SAD however, and combine well with light therapy.

    As a general principle, daily exposure to as much natural daylight as possible helps, as does regular exercise and looking ahead and making plans for springtime – sound advice in these strangest of times, even for those of us who do not suffer from SAD.