Boots WebMD Partners in Health
Return To Boots

Depression health centre

Select a topic to explore more.
Select An Article

Seasonal affective disorder

What is seasonal affective disorder?

With seasonal affective disorder (SAD) a person's depression becomes worse with certain seasons, usually winter.

A person affected by SAD may have a low mood and be less interested in their daily activities. They may also sleep more and become less active.

Symptoms may begin as the days get shorter during autumn and become worse during December, January and February, before improving in the spring.

People of any age can have SAD, which is thought to affect around 2 million people in the UK.

A less common form of SAD occurs in the summer and begins in late spring or early summer and ends in autumn. But in general, seasonal affective disorder starts in autumn or winter and ends in spring or early summer.

What causes seasonal affective disorder?

Hormones manufactured deep in the brain automatically trigger attitudinal changes at certain times of year. Experts believe that SAD is related to these hormonal changes. One theory is that reduced sunlight during autumn and winter leads to reduced production of serotonin in the brain. Serotonin is a neurotransmitter that has a soothing, calming effect. The result of there not being enough serotonin is feelings of depression along with symptoms of fatigue, carbohydrate craving, and weight gain.

SAD usually starts in young adulthood and is more common in females than in males. Some people with SAD experience very mild symptoms and feel out of sorts or irritable. Others have debilitating symptoms that interfere with relationships, productivity, and activities of daily living.

Because the lack of enough daylight during wintertime is related to SAD, it is seldom found in countries within 30 degrees of the Equator where there is plenty of sunshine all the year round.

What are the symptoms of seasonal affective disorder?

People with SAD have many of the usual symptoms of depression, including:

  • Decreased levels of energy
  • Difficulty concentrating
  • Fatigue
  • Increased/decreased appetite
  • Increased desire to be alone
  • Increased need for sleep
  • Weight gain/ weight loss

How is seasonal affective disorder diagnosed?

It is very important that you do not diagnose yourself. If you have symptoms of depression, see your doctor for a thorough assessment. Sometimes, physical problems can cause depression. But at other times, symptoms of SAD are part of a more complex mental health problem. A health professional should be the one to determine the level of depression and recommend the right form of treatment.

How is seasonal affective disorder treated?

There are different treatments for SAD, depending on the severity of the symptoms. Many doctors recommend that patients with SAD try to get outside as much as possible during the day-time to increase their exposure to natural light. If this is impossible because of the dark winter months, exercise, antidepressant medication, cognitive behavioural therapy ( CBT), light therapy (phototherapy), or a combination of these may help.

Next Article:

WebMD Medical Reference

Mind, body & soul newsletter

Look after your health
and wellbeing.
Sign Up

Popular slideshows & tools on BootsWebMD

woman_holding_head_in_pain
How to help headache pain
rash on skin
Top eczema triggers to avoid
boost your metabolism
Foods to lower LDL (bad) cholesterol
period_questions_answered
Tips to support digestive health
woman looking at pregnancy test
Is your body ready for pregnancy?
sick child
Dos and don'ts for childhood eczema
girl_sneezing_into_tissue
Treating your child's cold or fever
bucket with cleaning supplies in it
Cleaning and organising tips
adult man contemplating
When illness makes it hard to eat
woman holding stomach
Understand this common condition
cold sore
What you need to know