How Seasonal Affective Disorder works and how to treat it

Seasonal Affective Disorder can worsen in winter.
Seasonal Affective Disorder can worsen in winter. Photo credit: Getty

Many people may feel blue in the winter months - the cold, dark weather can be a real downer.

But for some this feeling of melancholy can become a real problem, going beyond a feeling of sadness and into one of depression. Seasonal Affective Disorder is thought to impact one in three people - but not much is known about the condition many people think is just the winter blues.  

What is SAD?

Seasonal Affective Disorder or SAD is a form of clinical depression prominent during winter months - its exact cause is unknown but it's thought to be linked to a variety of circumstances.

According to the Mayo Clinic, a reduced level of sunlight interrupts the body's natural circadian rhythm and leads to feelings of depression and fatigue. 

In winter with less hours of sunlight there is less of an opportunity to make vitamin D. Vitamin D is created when ultraviolet light hits cholesterol in the skin and converts it..

Studies have hypothesised a link between vitamin D and serotonin which suggests without adequate intake of vitamin D, serotonin cannot be produced.

During winter it's less likely vitamin D will be produced easily, causing a drop in serotonin which can cause unstable or lower moods. 

A change in melatonin levels has also been linked to SAD. 

Melatonin is triggered when it's dark to help you sleep - however if it's dark earlier, or during the day then your brain may overproduce melatonin leaving you drowsy and low on energy. 

SAD is more likely to be diagnosed in women and younger people and those who live further from the equator are more at risk. It's also thought to run in families and is more likely to affect people with pre-existing mental health conditions.

How do you know if you have SAD?

SAD and other forms of depression often overlap so it's important to seek medical advice if you experience the symptoms.

  • Some of the more common signs of SAD are
  • Depressed mood, feelings of sadness daily
  • Overeating or cravings for sweet/starchy food
  • Significant weight fluctuation
  • Oversleeping or insomnia
  • Decreased sex drive
  • Irritability 
  • Difficulty coping with usual daily tasks 
  • Withdrawal from others

According to Mental Health NZ, there is no test to diagnose SAD but a medical professional can analyse your symptoms and diagnose from there.

For a diagnosis the pattern of symptoms must have started in the autumn or winter months and lessened in the summer and spring for at least a two year period.

However this same pattern could be seen in a person during the depressed phase of bipolar affective disorder or other medical conditions so it is important your doctor spends time discussing your experience to rule these out.

Trouble sleeping and changes in appetite could be linked to SAD.
Trouble sleeping and changes in appetite could be linked to SAD. Photo credit: Getty


So I've got SAD, now what?

The treatment of SAD will revolve around your individual needs and range from therapy to man-made sunlight. It's important to understand what options are possible for you.

One of the ways people cope with SAD is via light therapy - artificial sunlight.

The American Psychological Association recommends people suffering SAD change their routine to get as much sunlight as possible - for example drinking coffee outside, or sitting near a window. However if that's not possible, or there is too little natural light available then there are light therapy boxes which mimic the sun.

The boxes are thought to ease other symptoms of SAD by mimicking daylight and restoring circadian rhythms. Dr Michael Craig Miller of Harvard Health Publishing says the light can reset areas of the brain.

"Bright light works by stimulating cells in the retina that connect to the hypothalamus, a part of the brain that helps control circadian rhythms," he said.

"Activating the hypothalamus at a certain time every day can restore a normal circadian rhythm and thus banish seasonal symptoms."

The Mayo Clinic recommends speaking with your GP before beginning light therapy as using the box for too long or increasing exposure too fast could exacerbate manic phases of bipolar.

Medical News Today also recommends therapy as a way of coping with SAD.

Cognitive Behavioural Therapy is thought to be effective by helping people to monitor and control their reactions to environments over time.

The American Psychological Association also suggests that CBT could have longer-lasting benefits than light therapy.

General lifestyle changes could also help people suffering SAD. Opening the curtains in the morning, trimming back trees which could be blocking light and forcing yourself to go outside for fresh air are all ways people can help ease their mental distress.

Regular exercise, a balanced diet and when possible a steady sleep schedule is all recommended.

However if these don't work and SAD is affecting your well being then there are medications available to treat the symptoms. Antidepressants such as selective serotonin reuptake inhibitors to increase serotonin levels.

Anyone who chooses to take medication to treat their SAD should do so at the instruction of a GP and check all prescribing information for side effects. 

Where to find help and support: