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  • Writer's pictureMalin Rignéus

How do I know I'm experiencing Seasonal Affective Disorder (SAD)?

The winter months in the Northern hemisphere can be quite challenging. The climate is often harsh and there is not much sunlight throughout the day. Many people find themselves being less energetic with low mood during this time of the year.

But how do you know if it's simply a general feeling of being a bit low, compared to experiencing what is often referred to as a full blown winter depression or winter blues?

Photo credit: Dev Asangbam via Unsplash

One way of determining this is to confirm if in general are you experiencing the following symptoms for several days at a time?

  • feeling imbalanced

  • low mood and listless most of the day, nearly every day

  • lack of energy, feeling sluggish

  • feeling under the weather

  • feeling hopeless, worthless, or guilty

  • increased need for sleep

  • changes in food intake, e.g., loss of appetite or carbohydrate cravings and weight gain

  • difficulty concentrating

  • losing interest in activities you used to enjoy

  • decreased sex drive

  • social withdrawal, e.g., feeling like hibernating

  • having thoughts of not wanting to live

If you noticed significant changes like these in your mood and behaviour for a period whenever the seasons change, you could be experiencing Seasonal Affective Disorder (SAD) (NIOMH, 2022).

This type of depression is related to the change of the seasons, it begins and ends about the same time each year. It’s prevalent in people who already have major depression or bipolar disorder, so it’s not a standalone diagnosis (BMJ, 2022).

Most people who suffer from SAD experience the symptoms in the autumn continuing during the dark winter months and often resolve during the spring and summer months.

Although not as common, some people experience SAD starting around spring until the end of the summer. Treatment may include light therapy, psychotherapy and medication (NHS, 2022).

What is the cause?

There is some evidence that experiencing winter depression could be hereditary, as some cases appear to run in the family. However, researchers conclude that SAD is most likely caused by the limited access to sunlight during the winter months in certain parts of the world.

Described in a simplified way, the lack of sunlight might stop a part of the brain called the hypothalamus from working properly which might affect the:

Melatonin production

Melatonin is a hormone passed to the blood when it’s dark and it tells the body when it’s time to sleep. As you’re probably aware of its commonly used as a sleep aid when we are experiencing jetlag.

Therefore, the increase of melatonin levels impacts our ability to stay awake. This substance also powers down your body functions as it prepares you to go to sleep.

Serotonin production

The lack of light might lead to lower levels of serotonin. This is sometimes called “the happy hormone”.

It’s a chemical that nerve cells produce, and it sends signals between your nerve cells. Serotonin is said to significantly influence our well-being and controls our mood, appetite, and sleep (Healthline, 2022).

Internal body clock (circadian rhythm)

Your body uses sunlight to schedule various important functions, e.g., waking up. Lower light levels may therefore disrupt this timing of your body clock making it more imbalanced that might lead to symptoms of SAD.

To conclude, there are quite a few symptoms that can indicate the presence of SAD and there are several possible causes to this type of depression. It is important to note that it needs to be significant changes in your mood and behaviour for several days in a row to be diagnosed as SAD.

If you are concerned and suspect that you might be experiencing this type of depression, please contact a medical health practitioner for a diagnosis and possible treatment. You can also read my blog on tips for self help to prevent or cope with SAD during the winter months.


Please note, as always the information provided is for educational and information purposes only and solely as a self-help tool for your own use.

The content provided is not a replacement for medical advice, diagnosis, or treatment. Don’t disregard or delay seeking medical advice because of information you have read here. Please check with your doctor before engaging in any new behaviour as recommended above. Depression can be rooted in deep seated beliefs or traumas that might need to be explored and worked through with a mental health professional.


Bestpractise; (2022)

Healthline,(2022), “Everything you need to know about serotonin.”

National Institute of Mental Health (2022),

National Health Service UK (NHS), NHS Overview Seasonal Affective Disorder


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