Seasonal Affective Disorder

What is Seasonal Affective Disorder?

Seasonal Affective Disorder (SAD) is a type of depression that happens at the same time every year and is related to changes in seasons. For most people, symptoms start in Autumn and continue through the winter months (also known as winter depression). For fewer people who suffer from SAD, symptoms are present from spring through to summer (summer depression).

Symptoms of SAD

The symptoms of SAD are similar to those of normal depression, the difference being that SAD occurs repetitively at particular times of the year. The main feature of SAD is that your mood and behavior shift along with the calendar.

Symptom degree varies. For some people, the symptoms are mild and manageable, but for others, the symptoms are severe and can have a huge impact on the quality of a person’s life. 

Some symptoms of SAD include:
  • problems with sleep

  • loss of interest in things you once enjoyed

  • having low energy/fatigue

  • persistent low mood

  • difficulty with concentration

  • feelings of despair, guilt, and worthlessness

  • changes to appetite and weight 

  • having frequent thoughts of death and/or suicide 

Winter SAD Symptoms

Symptoms specific to Winter depression are:

  • appetite changes, especially a craving for foods high in carbohydrates

  • oversleeping
  • weight gain

  • tiredness and/or low energy

Summer SAD Symptoms

Summer SAD begins in spring and ends in autumn. Symptoms specific to summer SAD are:

  • Poor appetite

  • Weight loss

  • Trouble sleeping

  • Agitation or anxiety


What Causes Seasonal Affective Disorder?

While the exact cause of SAD is not known, experts think that it is related to hormonal changes. Scientists believe that certain hormones made deep in the brain trigger attitude-related changes at certain times of the year.

Serotonin-Reduced sunlight can cause a drop in serotonin. Serotonin (the happy hormone) is a neurotransmitter that plays a significant role in our mood. 

Exposure to sunlight is thought to increase the brain’s release of serotonin. Because there is not as much daylight available to us in the winter months, it can affect the amount of serotonin produced.

Melatonin levels– Darkness prompts the pineal gland (positioned in the brain) to start producing melatonin. The change in season can disrupt the balance of the body’s level of melatonin, which plays a role in sleep patterns and mood.

Your biological clock (circadian rhythm)– Another theory of the cause of SAD is that the part of your brain that sets your body clock by the hours of daylight, is not working in the way it should. Your body clock will slow down and you may feel more tired and low in mood than usual.

Treatments for sad

Self Help for SAD 

There are things that you can do to help yourself manage your symptoms of SAD including:

  • try to get as much natural sunlight as possible
  • Sit near windows when you are indoors
  • make sure you eat a balanced, healthy diet
  • try as best you can to avoid stress
  • make your work and home environments as light as possible
Psychosocial treatments

Psychosocial treatments focus on both social aspects (how you interact with others)  and psychological aspects (how your brain functions).

The National Institute for Clinical Excellence (NICE) recommends that the same treatment be used for seasonal affective disorder as used for depression, which is Cognitive Behaviour Therapy (CBT), Counselling, and antidepressants.

Cognitive Behaviour Therapy

CBT focuses on the idea that the way we think and behave has an impact on the way that we feel. CBT works on changing the way we think about something, and what you do about it can change the way you feel about it.


Counselling is a talking therapy where you talk to a qualified counellor about your thoughts, feelings, and worries. Psychodynamic counselling is also a treatment option for SAD. This type of therapy aims to discover if anything from the past affects how you feel today.


Antidepressants are frequently used to treat SAD. The preferred type of anti-depressant used to treat SAD is selective serotonin reuptake inhibitors (SSRIs). SSRIs can take up to 4-6 weeks to reach their full effects, and some can produce side effects.

Light Therapy

Light therapy can be effective in treating SAD. The artificial light from a lightbox is thought to affect brain chemicals linked to mood and sleep, easing SAD symptoms. Lightboxes give off a very bright light and can come in various designs, such as lamps (SAD lamps) or wall-mounted fixtures. The brightness of the light is measured in Lux. The higher the Lux, the brighter the light.