Seasonal Affective Disorder

Seasonal Affective Disorder (SAD) is a debilitating mood disorder whereby, often severe symptoms of depression occur during the darker winter months of each year, which then disappear in the spring and summer. It differs from other forms of depression in that it varies with the seasons (i.e. normal mental health will be experienced for at least half of the year), and tends to be accompanied by other symptoms such as increased appetite, reduced activity and over-sleeping. A much milder form is sub-syndromal SAD, sometimes called the winter blues. SAD is thought to affect at least 1 in 50 people in the U.K., however, as the condition often goes undiagnosed, the actual figure may be greater. It is particularly common amongst younger people (onset typically occurring between the ages of 18 and 30), especially in women who are about four times more likely to be affected than men. A rarer form of SAD affects some individuals in the summer rather than the winter months, although research into this is currently sparse.

Symptoms of SAD typically develop as daylight hours get shorter, and are usually at their worst during December, January and February. Whilst the exact cause is unclear, it is likely that the reduced exposure to sunlight in the winter months causes an imbalance in brain chemicals such as serotonin, and the hormone melatonin, both of which affect mood, appetite, energy and sleep patterns. Effectively, the natural ability to regulate the body clock goes awry. A combination of lack of serotonin and an increase in melatonin can trigger a depression in the susceptible individual, although why some people suffer and others don't is unclear. Modern life-styles where a person goes to work in the dark, and comes back home in the dark, may be conducive to the development of SAD. As well as environmental and lifestyle factors, genetics may also have a part to play, as about 1 in 7 first-degree relatives of people affected also develop SAD. For some, symptoms can cause considerable distress, and impair quality of life in winter. Weight gain is common as appetite increases and activity levels decrease. Lethargy and decreased productivity may be seen as both causes and symptoms of SAD. It may be difficult to carry out a normal routine; there may be anxiety accompanied by feelings of being unable to cope; social problems may develop such as withdrawing from contact with others. Despondency can occur for no apparent reason; loss of libido and interest in previously enjoyed activities is common. Generally the sufferer feels run-down, unhappy and stressed.

Whilst difficult to live with, there are a number of treatments and medications available that can improve the condition, as well as self-help measures you can take. Early diagnosis will be important, and once you know you have SAD it is advisable to take preventive measures in early autumn before symptoms develop. Treatment options include light therapy, talking therapies such as cognitive behavioural therapy, and medications such as anti-depressants. Combinations of these may be most effective. Self-help measures include taking regular exercise and exposing yourself to as much natural daylight as possible, as these can help reset the body clock, and aid a return to normal sleep patterns. Learning relaxation techniques can be very helpful in combating anxiety and stress, which will improve overall mood.


  • feelings of despondency and hopelessness characteristic of depression
  • lack of energy, and difficulty carrying out a normal routine; inactivity
  • over-sleeping, especially difficulty waking up in the morning
  • increased appetite and a tendency to overeat, leading to weight gain
  • cravings for sweet foods and carbohydrates
  • loss of interest in previously enjoyed activities
  • withdrawal from friends, family and social activities
  • feelings of anxiety and an inability to cope
  • difficulties in concentration; frustration and irritability
  • feelings of worthlessness and guilt
  • noticeable change of mood in spring, sometimes accompanied by restlessness and excessive energy


If you believe you may suffer from SAD it will be a good idea to visit your GP. To be diagnosed as having SAD you will have experienced a number of the above mentioned symptoms for two or more consecutive years, during the autumn and winter months only, which disappear once spring arrives. There will have been no non-seasonal depressive episodes during this time; in other words, other forms of depression will need to be ruled out. If you have SAD, it is likely that you will have experienced increased appetite, cravings for sweet things, and excessive sleepiness, features specifically associated with this disorder (but usually absent in other depressive illnesses). It may take a few years for you and your doctor to recognise that your recurring episodes of depression follow a seasonal pattern, and the condition sometimes goes undiagnosed. It may be helpful to keep a mood diary to track when mood and other symptoms arise, and when they disappear again, and to share this information with your GP to help establish what your particular pattern is, and whether or not SAD is indeed an accurate diagnosis.

Treatment with Medication

Selective serotonin re-uptake inhibitors (SSRIs) may be helpful for some of the symptoms of SAD, including fluoxetine, sertraline or paroxetine. By increasing serotonin levels in the body, these can help reset the body clock, and re-establish a normal sleep/wake pattern. Anti-depressants will be most effective if you can start taking them before symptoms develop in autumn, and continue their use until spring when symptoms disappear naturally.

Light Therapy

For some people, exposure to bright artificial light can dramatically alleviate the symptoms of SAD. The increase in melatonin, and reduction in serotonin associated with shortened winter daylight hours, and consequent depression, can be reversed with the use of a SAD lamp, with the advantage of this being drug free. Light intensity is measured in lux, and your SAD lamp should produce at least 2,500 lux - about 10 times that of ordinary light bulbs. The light box should ideally be used twice a day for about 30 minutes a time. As with drug therapy, treatment with a light box should commence in autumn as soon as symptoms occur, and should be used on a daily basis until spring. This requires time and commitment, but it is well worth persevering, and improvement in symptoms is generally noticeable within the first week of use; however, symptoms continue to improve over several weeks use. A dawn simulation lamp can also be effective in resetting the body clock, and improving mood and energy levels.

Talking Therapies

Cognitive Behavioural Therapy (CBT) is a psychological treatment which helps to change the way you think, feel and behave. Although often offered in the short-term only, CBT has been shown to have long lasting effects, and can help prevent future relapses of SAD. A combination of light therapy and CBT has been shown to significantly reduce symptoms in sufferers, both in the short and long-term.

Although SAD has been shown to have a biological basis, it is often accompanied by negative automatic thoughts, pessimistic attitudes, withdrawal from social activities, and rumination, and CBT can be particularly helpful in targeting these negative thoughts and behaviours. During CBT, the sufferer will learn skills which can alleviate the depressive symptoms. These will include learning to think positively, increasing enjoyed activities, and socialising with other people, all of which have been shown to improve mood. Improved coping with winter may include challenging negative thoughts related to the darker months. The learned skills will help the sufferer to cope with subsequent winters, and to develop a personal relapse prevention plan. For those SAD sufferers who do not improve with light therapy alone, CBT offers an effective adjunct or alternative therapy.

Self-Help Measures

In addition to the above, a number of self-help measures have proved effective in reducing the symptoms of SAD. Exposure to as much daylight as possible is important, as is exercise, so a walk in the fresh air, for example, will have a two-fold benefit. It will be helpful to get into a regular exercise routine as this promotes feel-good hormones. When you are inside, try to sit near a window whenever possible. Eating a well balanced diet, and keeping a regular sleep schedule are beneficial. It may be wise to tackle major projects in the lighter months, and keep stress to a minimum when you are suffering symptoms. Relaxation tapes can help with this, and improve overall mood. Schedule pleasant activities into your week, and try to avoid withdrawing from social events, as interactions with others can also bolster your mood. If you confide in your family and friends, they may be able to offer help and understanding. Finally, remember you are not alone in suffering SAD, and it might be worth investigating whether there is a support group in your area.