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What is Seasonal Affective Disorder (SAD)?

Seasonal affective disorder (SAD) is a type of depression that's related to changes in seasons — SAD begins and ends at about the same times every year. If you're like most people with SAD, your symptoms start in the fall and continue into the winter months, sapping your energy and making you feel moody. SAD has a lot in common with depression


The main symptoms of SAD are similar to those of depression, but happen in the winter.

  • low mood
  • lack of interest and enjoyment in life
  • Often also these symptoms occur also:
  • low energy
  • being less sociable
  • being less irritable
  • less interest in sex.
Common symptoms of SAD which are different from those in most depression are:
  • sleeping more
  • eating more


Who is affected by SAD?

Like other types of depression, SAD is most common in women during the years when they can have children. It is about three times more common in women than it is in men. SAD is less common in children and in older adults, affecting men and women equally.


How common is SAD?

Many of us will feel different in the winter with symptoms of feeling slightly tired, sleeping a bit more and perhaps gaining some weight. It is a bit like hibernation in animals. If your symptoms are bad enough to interfere with your life, you may well have SAD. In the UK, about 3 people in every 100 have significant winter depressions.


What treatments are available for SAD?

SAD can be treated in the same way as depression. Treatment usually includes self-help and lifestyle changes, talking therapies and antidepressant medication. Light box treatments are also popular and have some evidence.



Some symptoms of SAD can create extra problems which make you feel even worse – 'vicious circles':


  • If it is dark and you feel tired all the time, you will probably do less – and this can make SAD worse. Try to get as much natural sunlight as possible. Take a walk during daylight hours or carry on any exercise you would normally do. Remind yourself that days will get longer again in the spring.
  • Sleepiness, lack of motivation and irritability can all cause problems at home, with your friends, and at work. The feelings of not getting things done can make you feel stressed. Tell your family and friends so that they can understand what is happening and be supportive.


Light therapy

The idea is to try to provide extra light and to make up for the shortage of daylight in winter. A "light box" is used. Its light is like sunlight, but without the ultraviolet rays, so it is not harmful to the skin or the eyes. It may help tell the brain to make less of a hormone, melatonin.


A light box is usually used for 30 minutes to an hour each day. It is most helpful if you use it at breakfast time. Light therapy works quite quickly. If it is going to help, most people will notice some improvement in the first week.


Fortunately, any side-effects are usually mild. They include headache, nausea or blurred vision. It is usually best not to use a light box after 5.00 pm because you may then find it hard to get to sleep.


Dawn-simulating alarm clocks are also used. These come on dimly about an hour before waking up time and gradually get brighter. They can be helpful if you find it hard to wake up on winter mornings.



Antidepressants may be helpful in SAD.

Any medication which would make people more tired or sleepy should be avoided, and so SSRI antidepressants are usually used.

The best evidence is for the use of sertraline, citalopram or fluoxetine. In SAD, it is usual to start antidepressants in the autumn and stop them in the spring.


Cognitive behavioural therapy (CBT)

There is some evidence that CBT can help winter depression and may prevent it coming back in future winters. CBT is a treatment for anxiety and depression in general.  You have weekly sessions with a therapist and do some homework, like keeping a diary.

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