Seasonal affective disorder (SAD)

Seasonal affective disorder (SAD) has a lot in common with depression. Have a look at our resource on depression before reading this information.

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

• low mood 
• lack of interest and enjoyment in life
• low energy
• being less sociable
• being more irritable
• less interest in sex.

Common symptoms of SAD which are different from those in most depression are:

• sleeping more
• eating more.

If you have SAD, you may find it hard to wake up on a winter's morning and can often feel sleepy during the day. You may crave chocolate and high carbohydrate foods, such as white bread or sugary foods. You might find you put weight on.

SAD gets better in the spring. Around a third of people with SAD have a time when they feel more energetic than usual during the spring and summer.

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 males and females equally.

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 might have SAD. In the UK, about 3 people in every 100 have significant winter depression.

We do not fully understand what causes SAD, but the reduced amount of light in the winter seems to be important. It is more common where it is dark in the winter. There has been a lot of research exploring how daylight can influence appetite, wakefulness and mood.

However, people living in very northern areas do not appear to suffer more SAD than people living further south, so other factors may be important. Also, some people report that they feel depressed in the summer instead.

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.

Self-help

Some symptoms of SAD can create extra problems which make you feel even worse:

• 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.
• If you are eating more, you may put on too much weight which makes you feel worse. Remind yourself that most people put on weight in autumn and early winter.
• Sleepiness, lack of motivation and irritability can all cause problems at home, with your friends, and at work. The feeling 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

Light boxes are used to try to provide extra light to make up for the shortage of daylight in winter. Light boxes give off light 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 called 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 5pm 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.

Medication

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.

A recent review of the evidence did not find a large effect. Speak to your doctor to find out more about antidepressants.

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. Have a look at our information on CBT.

What is the best treatment?

For mild symptoms, the self-help measures described here will usually be enough.

If your symptoms are worse, the first choice is usually between a light box and antidepressants. The choice will often depend on what is available, what is convenient and what you prefer.

• Seasonal Affective Disorders Association (SADA): The UK's non-commercial support organisation for SAD, and a voluntary organisation and registered charity. Provides information for the public and for health professionals and is dedicated to advising and supporting people with SAD nationwide.
• Winter Blues:  Everything you need to know to beat Seasonal Affective Disorder by Norman E. Rosenthal, The Guilford Press; Fourth Edition (September 4, 2012) is an excellent source of further information.
• Light is a Right: A Guide to Wintering Well - This digital booklet was developed by researchers from the Universities of Glasgow and Edinburgh, and draws on the experiences of people living with Seasonal Affective Disorder.

Light boxes

There are numerous companies selling light boxes, and some will offer a trial-and-return so you can return it if it is not helpful. Search on the internet or contact SADA.

References

Anonymous (2009) Management of seasonal affective disorder. Drugs and Therapeutic Bulletin, 47, 128-132.

Golden, BN et al (2005) The efficacy of light therapy in the treatment of mood disorders:  a review and meta-analysis of the evidence.  American Journal of Psychiatry, 162, 656-662.

Eagles, JM (2009) Light therapy and seasonal affective disorder. Psychiatry, 8, 125-129.

Thaler K, Delivuk M, Chapman A, Gaynes BN, Kaminski A, Gartlehner G. Second-generation antidepressants for seasonal affective disorder. Cochrane Database of Systematic Reviews 2011, Issue 12.

Johnsen et al.: Is there a negative impact on mental distress and sleeping problems in the sub-arctic? Findings from the cross-sectional Tromsø Study. BMC Psychiatry 2012 12:225.

Credits

Produced by the Royal College of Psychiatrists' Public Engagement Editorial Board. This information reflects the best available evidence available at the time of writing.

• Series editor: Dr Philip Timms
• Original author: Professor John Eagles
• Reviewed by: Dr Wojtek Wojcik and Dr Robin Berger
• Service user/carer input: Depression Alliance