Seasonal Affective Disorder

Learn about SAD, signs to look for, how your doctor determines if you have SAD and treatment options
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Found in: Mental Health Conditions
Date: September 2022

About SAD

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

It’s normal to feel and behave a bit differently during the colder, darker months. Most people find they sleep more, eat more or crave different foods, want to spend more time “hibernating” at home or by themselves, and generally feel less energetic and cheerful during these times. It is part of the natural cycle of the seasons and can be a useful time for resting and slowing down.

However, the symptoms of SAD (sometimes called “depressive disorder with seasonal pattern” or the “winter blues”) can be very distressing and challenging to manage, and it can have a severe impact on your life. For some, SAD is mild and, although it is unpleasant, it 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.

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. Less commonly, some people experience the opposite, with symptoms appearing in spring or summer.

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 clocks go out of step. SAD is less likely to occur in New Zealand than in countries that have little sunlight in winter.


Signs to look out 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 or low mood and can include:

  • A persistent low, sad or depressed mood. This is experienced in varying ways by people. You may feel very sad or empty, you may have no feelings, or you may feel in pain.
  • Loss of interest and pleasure in usual activities. You may find you don’t enjoy the things you usually would, such as socialising, playing sport or sex.
  • Irritable mood. This may be the main mood change you notice, rather than sadness.
  • 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. You may sleep too much. You will probably wake feeling unrefreshed by your sleep.
  • Change in appetite. You may not feel like eating and, as a result, will have lost weight. Or you may have increased appetite, often without pleasure in eating.
  • Decreased energy and tiredness. These feelings may be so severe that even the smallest task seems too difficult to finish.
  • Reduced contact with others. You may withdraw from doing things and from contact with others.
  • Thoughts of hopelessness and death. You may feel there is no hope in life, wish you were dead or have thoughts of suicide.
  • Difficulty thinking clearly. You may have difficulty in concentrating. You may not be able to read the news or watch television. You may also have great difficulty making even simple everyday decisions.
  • Agitation or anxiety. This is more common in summer-onset SAD, where symptoms affect you in the warmer months.

How the doctor determines if you have SAD (diagnosis)

There is no test to diagnose SAD. Your doctor will listen to your description of your symptoms and make an assessment based on that. 

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.

Some SAD symptoms are similar to other conditions, so your doctor will want to rule these out by getting a full understanding of your experience. They may carry out tests for this reason, and it may be helpful for them to hear your whānau/family’s perspective, if you are comfortable with this.

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 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. Your doctor may recommend starting treatment with an antidepressant before your symptoms begin each year.

If you are pregnant or breastfeeding, medication may still be an option for you. Talk with your doctor about what is best for you and your circumstances.   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
  • what the process of stopping taking them (withdrawal) could look like.

Remember that it may take several weeks to notice full benefits from an antidepressant. 

Other strategies to support recovery

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 check-up with your GP. Being in good physical health will also help your mental health.

Supporting your own wellbeing

Other people with SAD have found the following things helpful:

  • Make your environment sunnier and brighter by opening curtains and trimming tree branches that block sunlight into your home.
  • Sit closer to bright windows while at home or in the office.
  • Head outside as often as you can – even on an overcast day, outdoor light can help, particularly if you spend time outside within two hours of getting up.
  • Find ways to maintain connections with people in your life that don’t involve going out too much in the cold, such as talking online or inviting friends to your home. 
  • If possible, plan a holiday during winter – either to get a break from the cold or just to have something pleasant to look forward to.
  • Look into supplements that may help support your physical health.
  • Find someone at work, school or wherever else you spend a lot of time who understands your experience and can support you if you are having a hard time.
  • Do what you need to do to support your own wellbeing, even if others don’t understand – you may find people in your life underestimate the impact SAD has on you.  
  • Remember that wanting to “hibernate” during winter is natural. Be kind to yourself and allow yourself to rest in ways that feel right for you.

Thanks to Joanna Macfarlane, clinical psychologist, and members of the Thriving Madly peer support network in Christchurch for reviewing this content. Date last reviewed: September, 2022.

Thanks also to Sutherland Self-Help Trust for making the 2022 updates possible.