Seasonal affective disorder (SAD)
Seasonal affective disorder (SAD)
Seasonal affective disorder, usually shortened to SAD, is a form of depression that follows the seasons. For most people the symptoms start in autumn, as the days grow shorter, and reach their worst in December, January and February. Because of this pattern, it is sometimes called 'winter depression'.
In most cases, the symptoms begin to ease in spring and then go away altogether.
Common Symptoms
⚠️ This symptom list is for educational purposes. Having these symptoms does not mean you have this condition. See a doctor for proper diagnosis.
Medicines Commonly Used
⚠️ These medicines are commonly used for confirmed diagnoses of this condition. This is NOT a recommendation or prescription. Treatment must be determined by your doctor.
No medicines have been linked to this condition yet.
Causes
What causes SAD?
No one knows the exact cause of SAD. The symptoms of depression are thought to be linked to getting less sunlight.
One theory is that a lack of light in the winter months affects your mood, sleep and appetite, which changes how you feel.
Diagnosis
SAD can be hard to pin down, because many other kinds of depression cause very similar symptoms. It may take a few years before you and your doctor notice that your low moods are following a regular seasonal pattern.
Your doctor may do a mental health assessment. As part of this, you may be asked about:
- your mood
- your lifestyle
- your eating habits
- your sleeping habits
- whether your thoughts and behaviour change with the seasons
- your own medical history
- your family's medical history
Your doctor may also do a short physical check-up to rule out other reasons for your symptoms.
To diagnose SAD, your doctor will consider whether:
- you have had symptoms during the same season for 2 or more years in a row
- your spells of depression are followed by periods when you feel well
- there is any other explanation for your seasonal mood changes
Treatment
Treatment for SAD
Your GP will recommend the most suitable treatment option for you. This may involve using a combination of treatments to get the best results.
Self help for SAD
Work through our self help guide for depression that uses cognitive behavioural therapy.
Change Mental Health has some tips for managing SAD
Talking therapy
You might be offered cognitive behavioural therapy (CBT) which is a type of talking therapy. It helps you change how you think and react to situations that are making you unhappy.
Counselling is another type of talking therapy where you talk to a trained counsellor about your worries and problems.
Light therapy for SAD
Light therapy simulates the sunlight that’s missing during the darker winter months.
However, there’s mixed evidence about the effectiveness of light therapy.
Light therapy may be more effective if used first thing in the morning. Some people find looking at a very bright light uncomfortable.
Light therapy produces short-term results. It may help to relieve your current symptoms, but you may still be affected by SAD next winter.
When buying a light box, make sure that you choose one that is:
- made by a fully certified manufacturer
- medically proven to treat SAD
The SAD Association can provide a list of recommended manufacturers.
Very bright light may not be suitable if you:
- have an eye problem or your eyes are particularly sensitive to light
- are taking certain types of medication, such as antidepressants
- have epilepsy
Speak to your GP if you’re unsure about a particular product or if you experience any side effects while using light therapy.
Antidepressants for SAD
Antidepressants are often only prescribed for SAD when the symptoms are severe. This is because there’s limited evidence that they’re effective.
It’s thought that they are most effective if they’re taken at the start of winter (before the symptoms appear) and continued until spring.
It can take between 4 and 6 weeks for antidepressants to take full effect. It’s also important to continue to take the medication as prescribed, even if you start to feel better.
Read more about antidepressants
Don’t include personal information e.g. name, location or any personal health conditions.