Winter is coming — and so too are shorter and cooler days.
You might feel like you have a case of the winter blues, but how can you differentiate between that and something more serious, known as seasonal affective disorder (SAD)?
Here’s what to know.
What is seasonal affective disorder?
SAD is a type of depression that is related to changes in the seasons. It’s also known as winter depression, though some research suggests people can develop it in the warmer months.
While you might at times feel down throughout the cooler months, SAD is a clinical condition. Those with SAD might have symptoms similar to major depression, including disrupted sleep, low self-esteem, low physical activity levels, and cravings for carbohydrates.
People with SAD usually experience it at the same time each year.
“[SAD] is a form of clinical depression,” said Nick Titov, director of online mental health clinic MindSpot and a professor at Macquarie University. “It’s a lot more serious than the everyday sadness and blues.”
SAD is also said to be very rare in Australia, and more common in the northern hemisphere’s colder climates where some places receive very few hours of sunlight — less of which is thought to be a trigger for SAD — during winter.
Professor Greg Murray, director of Swinburne University’s Centre for Mental Health, told the ABC in 2020 he believed the condition affects “about one in 300 Australians”.
What causes seasonal affective disorder?
It’s thought disruption to the body’s natural circadian rhythm, due to less sunlight and shorter days, might be part of the cause of SAD.
“SAD’s a unique one in that the symptom onset is closely tied to the reduction of sunlight in the day, some people have this predisposition where their body reacts very strongly to lack of sunlight,” said Luke Martin, a clinical psychologist and senior adviser at mental health and wellbeing support organisation Beyond Blue.
Naturally occurring hormones, such as melatonin, might also play a role in the onset of SAD.
Melatonin is produced in the body when it’s dark outside. Longer and darker days increase melatonin production, which can contribute to increased sleepiness and lethargy. Some studies suggest that those who have SAD may produce too much melatonin.
“When your body’s internal clock starts getting confused about the daytime hours, or the nighttime hours, it impacts the mood state,” Martin said.
Serotonin, another hormone, plays an important role in regulating mood and is one of the body’s ‘feel-good chemicals’. Exposure to sunlight is thought to increase serotonin production.
Low serotonin levels in the brain are thought to play a role in the development of depression.
Some studies suggest that people with SAD have difficulty regulating their serotonin production as well and may not produce enough of it.
How can you ease seasonal affective disorder?
“We know that there is this tendency for the symptoms of SAD to start in late autumn, and they increase in severity throughout winter,” Martin said. “If you notice the symptoms … the sooner you get support the sooner you’ll get well again.”
Medication, psychological interventions, and bright light therapy — which involves sitting in front of a bright light for about thirty minutes — might help relieve symptoms.
Martin also stressed the importance of getting outside.
“Your brain really needs to know the patterns of the night and day,” he said. “So get out in the morning and get some sunlight.”
Titov said some people might be more active in summer than they are in winter, and added that people should try to maintain a routine.
“Some people restrict their activities during winter, and we suspect that this may increase their vulnerability to symptoms of depression.”
This article contains general information only. For advice relating to your personal situation, see a qualified medical practitioner.
Readers seeking mental health support can contact Lifeline on 13 11 14, on 1300 224 636 or 13YARN on 13 92 76.
Samantha Parker 
Tyler Mitchell