Aria Campbell-Danesh DClinPsy

Mind. Body. Food.


Are You Affected By Seasonal Affective Disorder (SAD)?

One-third of SAD cases may morph into non-seasonal depression.

Posted Dec 17, 2019

Ben White/Unsplash
Source: Ben White/Unsplash

What are the symptoms of SAD?

Seasonal affective disorder (SAD) is a type of major depression that occurs during particular times of the year. While SAD is considered to be a sub-type of depression, studies indicate that in 33-44% of cases, SAD turns into non-seasonal major depression. 

SAD is sometimes referred to as “winter depression” because the symptoms usually begin and worsen during the autumn/winter seasons. Symptoms typically resolve during spring/summer, although some individuals may experience symptoms during summertime. There is a rare form of seasonal depression known as “summer depression”, which begins in late spring and ends in the autumn.

Diagnosis of SAD is generally based on depression cycles on a regular basis during autumn/winter, with remission of symptoms in spring/summer, and seasonal symptoms for at least two consecutive years. 

People with SAD experience mood changes and symptoms similar to non-seasonal depression, including:

  • Low mood
  • Marked loss of interest and pleasure in everyday activities
  • Decreased motivation
  • Decreased energy and fatigue
  • Feeling worthless or guilty
  • Decreased libido
  • Impaired concentration
  • Irritability 

There is a specific cluster of symptoms that are characteristic of winter SAD: increased sleep with a strong desire to sleep during the daytime; increased appetite and cravings, especially for carbohydrates; and weight gain.

SAD is more than simply experiencing the “winter blues.” The symptoms can be emotionally distressing and interfere with day-to-day functioning.

How is SAD caused?

The exact causes of SAD are not fully understood. However, scientists have linked SAD to less sunlight exposure during shorter autumn and winter days. 

The most established theory is that lack of sunlight leads to hormonal changes in the brain. Reduced exposure to sunlight may prevent an area of the brain known as the hypothalamus from functioning properly, resulting in a biochemical imbalance. For instance, there may be lower production of serotonin, the ‘happy chemical’ in the brain involved in regulating our mood. When neural pathways that affect emotion regulation are disrupted, our mood, energy levels and appetite can be impacted. In people with SAD, the brain may produce higher than normal levels of melatonin, the ‘sleepy hormone’ associated with onset of sleep. Lower levels of sunlight may also throw off the body’s natural circadian rhythm or ‘internal clock’, resulting in SAD symptoms. 

In the US, up to 6% of adults have major depression with a seasonal pattern. The average age that someone first experiences SAD is 27 years. SAD is most common in females of reproductive age, with the disorder being four times more common in women than men during this time. Prevalence rates reduce in older age, with older males and females being affected equally. The disorder is less common amongst children, and the rates are similar in boys and girls. There appears to be a genetic component, as the disorder can run in some families. You’re more likely to have SAD if a close family member is affected. Countries with sunshine all year round have lower rates of SAD: the further away you live from the equator, the less likely you are to have SAD. 

How can SAD be treated?

SAD symptoms typically resolve during spring and summer. However, symptoms can improve more quickly with treatment.

The National Institute for Health and Care Excellence (NICE) recommend that SAD should be treated in the same way as non-seasonal depression. 

Effective treatments for seasonal and non-seasonal depression include talking therapies, for instance CBT, antidepressant medications such as selective serotonin reuptake inhibitors, and lifestyle changes. Individuals with SAD are often encouraged to spend as much time as possible in natural sunlight, to plan and take part in pleasurable activities, exercise regularly (especially outdoors) and to eat a healthy diet.

Another popular treatment for acute episodes of SAD is light therapy. This involves exposure to bright light from a light therapy box (which filters out harmful ultraviolet rays). Individuals are often advised to sit in front of a light therapy box for 20 minutes or longer on a daily basis, for instance first thing in the morning during winter months.