Also known as seasonal affective disorder, depressive disorder with seasonal pattern

Seasonal affective disorder (SAD) is a form of depression that's related to the change of season from summer to winter, and which affects people through the winter months.

For some, SAD may be mild and doesn’t interfere too much with their daily functioning. But for others SAD is seriously disabling and prevents them from functioning normally without continuous medical treatment.

You may hear it called depressive disorder with seasonal pattern, and you may have even heard of people talking about the ‘winter blues’. It’s all the same thing. It is less likely to occur in New Zealand than in countries who have little sunlight in winter.

Like depression, SAD can affect how you feel and behave for weeks or months at a time. When you are depressed, your low mood lasts, affecting your sleep, energy levels, relationships, job and appetite. The difference between depression and SAD is that if you experience SAD your symptoms will appear around the end of autumn, and continue through until the days get longer and sunnier in spring.

You should not ignore SAD, as it can be effectively treated.

If you think you are experiencing SAD, talk to your doctor. Treatment may be as simple as staying out in the sun for a time each day, or it may mean being treated for depression through the winter months.

It’s important that you take SAD seriously as it can get worse and lead to other problems such as substance abuse, school or work problems, loss of interest in relationships and even suicidal thoughts.

The risk of suicide in people experiencing any form of depression is significant.

It’s important that if you are having any suicidal thoughts you seek help immediately.

What causes SAD?

The exact cause of SAD is unknown. It may be that the drop in sunlight hours affects the body’s chemical balances and make our body clock go out of step. These changes in the brain can make some people vulnerable to SAD.

Signs to look for (symptoms)

Symptoms of SAD usually build up slowly through late autumn and winter months. Symptoms are usually the same as with other forms of depression and can include:

  • A persistent low, sad or depressed mood. This is described in varying ways by people, especially if they are from non-European cultures. The person may describe feeling very sad, empty, having no feelings, or may complain of pain.
  • Loss of interest and pleasure in usual activities. This is a reduced ability for enjoyment. It includes loss of interest in sex.
  • Irritable mood. This may be the main mood change, especially in younger people, and in men.
  • Change in sleeping patterns. Most commonly reduced sleep, with difficulty getting to sleep, disturbed sleep, and/or waking early and being unable to go back to sleep. Some people sleep too much. Most people with depression wake feeling unrefreshed by their sleep.
  • Change in appetite. Most often people do not feel like eating and, as a result, will have lost weight. Some people have increased appetite, often without pleasure in eating. This is often seen in those who also sleep more.
  • Decreased energy and tiredness. These feelings may be so severe that even the smallest task seems too difficult to finish.
  • Reduced contact with others. As a result of feeling bad about themselves, people may withdraw from doing things and from contact with others.
  • Thoughts of hopelessness and death. The person may feel there is no hope in life, wish they were dead or have thoughts of suicide.
  • Difficulty thinking clearly. People may have difficulty in concentrating. They may not be able to read the paper or watch television. They may also have great difficulty making even simple everyday decisions.

How the doctor determines if you have SAD (diagnosis)

There is no test to diagnose SAD. A diagnosis is made by your doctor based on whether you have some or all of the typical symptoms. For a diagnosis of SAD, the pattern of symptoms starting during autumn/early winter and reducing in spring/early summer must have occurred during at least a two-year period, with no other episodes of depression during that same timeframe.

For this reason it’s important that your doctor spends time with you to get a full understanding of the difficulties you have had, both from you and your family’s perspective.

While SAD could be responsible for the symptoms listed above, the same picture can be seen with the depressed phase of bipolar affective disorder and in some medical conditions.

This is why your doctor may do tests necessary to rule out these conditions.

Treatment options

The treatment of SAD can involve a number of aspects, each of which is tailored to your individual needs. For most, a combination of light therapy, medication and talking therapies such as counselling will be effective.

Light therapy

Increased exposure to sunlight can improve symptoms of SAD. For this reason your doctor may suggest outdoor time each day, or even light therapy, which involves sitting in front of special lamps every day. These special light boxes give around 10 times the intensity of ordinary home lighting and have been shown to be very effective.

Talking therapies and counselling

Supportive counselling is a treatment for milder forms of depression, where it is as effective as antidepressant medication. Your doctor will explain what is available locally and which type of talking treatment is most suitable for you. 


Your doctor may prescribe antidepressants. Finding the right medication can be a matter of trial and error – there is no way to predict which medication will be effective and tolerated (have fewer troublesome side effects) by any one person. 

If you are prescribed medication you are entitled to know:

  • the names of the medicines
  • what symptoms they are supposed to treat
  • how long it will be before they take effect
  • how long you will have to take them for and what their side effects (short and long-term) are. 

If you are breast feeding no medication is entirely safe. Before making any decisions about taking medication at this time you should talk with your doctor about the potential benefits and problems.

Complementary therapies

The term complementary therapy is generally used to indicate therapies and treatments that differ from conventional western medicine and that may be used to complement and support it. Certain complementary therapies may enhance your life and help you to maintain wellbeing. In general, mindfulness, hypnotherapy, yoga, exercise, relaxation, massage, mirimiri and aromatherapy have all been shown to have some effect in alleviating mental distress.

Physical health

It is also really important to look after your physical wellbeing. Make sure you get an annual checkup with your GP. Being in good physical health will also help your mental health.

Thanks to Janet Peters, registered psychologist, for reviewing this content. Date last reviewed: 2014.