Seasonal Affective Disorder (SAD) is a form of depression associated with seasonal changes. For most sufferers, the symptoms of SAD begin in autumn and persist through the winter months. Less commonly, SAD can affect individuals in the spring and summer. Unlike other depressive episodes, the symptoms of SAD appear at the same time each year. 

Although it may be a widespread condition, SAD can be challenging to diagnose and treat. Many individuals who live with it do not even realise what they are experiencing.

How to know when feeling sad might be SAD

Many people go through short periods of time where they feel down or out of sorts and sometimes, these mood changes begin and end when the seasons change. But if your symptoms are more severe and affect how you feel, think, and handle daily activities, you may be suffering from SAD.

The signs and symptoms of SAD are the same as those of major depression with a few additional season-specific symptoms. The symptoms of major depression include:

• Feeling depressed most of the day, nearly every day
• Losing interest in activities you once enjoyed
• Experiencing changes in appetite or weight
• Having problems with sleep
• Feeling sluggish or agitated
• Having low energy
• Feeling hopeless or worthless
• Having difficulty concentrating
• Having frequent thoughts of death or suicide

For winter-pattern SAD, additional symptoms may include:

• Sleeping more than usual
• Overeating, especially high-carbohydrate foods
• Weight gain
• Low energy and social withdrawal 

For the rarer summer-pattern SAD, additional symptoms may include:

• Insomnia
• Poor appetite
• Weight loss
• Increased agitation
• Increased anxiety
• Irritability leading to episodes of violent behaviour

As with all forms of depression, no two people with SAD experience it in exactly the same way. Different people will experience varying combinations of symptom types and severity. If you feel that you may be experiencing SAD, it is essential to consult with a mental health care provider. A simple questionnaire can be the first step towards a diagnosis.

What causes SAD?

While there is no known specific cause, SAD occurs more often in women than in men, and it is more common in those living farther north, where there are shorter daylight hours in the winter.

Scientists believe various other factors may also be to blame:

• Genetics. SAD is more common in people who have relatives with other mental illnesses, such as major depression or schizophrenia.
• Circadian rhythm. SAD sufferers may have an impaired biological clock preventing them from adapting to changing day/night cycles.
• Serotonin levels. Reduced sunlight can lead to a drop in serotonin levels (a “happy hormone”) which affects mood.
• Melatonin levels. Season changes cause overproduction of this “sleep hormone” causing sleepiness and depressed mood.
• Vitamin D. Deficiencies of the “sunshine vitamin” during the winter months may exacerbate the processes discussed above. 

How is SAD treated?

Fortunately, various treatment options are available to make your seasonal mood changes more bearable.

Lifestyle

Don’t underestimate the power of mood-boosting lifestyle habits. Be sure to exercise regularly (outside, if you can), optimise your sleep, manage your stress, eat a healthy diet, and socialise with others.

Light therapy

Light therapy is a mainstay of SAD treatment and has been since the 1980s. Often, 30 minutes of direct sunlight exposure in the mornings can be enough to ward off symptoms. If this isn’t an option, special light boxes can simulate the effect of the sun.

Psychotherapy

Cognitive behavioural therapy is a type of talk therapy aimed at helping people learn how to cope with difficult situations. 

Medication

Antidepressant medications, called selective serotonin reuptake inhibitors, can treat SAD symptoms and significantly enhance patients' moods. Vitamin D may also be prescribed for those who are deficient.

The bottom line

There aren’t many people who like the cold and dark of winter, but if your winter blues are more than just a funk, it might be time to seek help. Whether it's light therapy, medication, psychotherapy, or lifestyle changes, there are many solutions to manage seasonal depression and enhance your quality of life. You are not alone.