Are some people more at risk of getting SAD in winter?

Have you been feeling down this winter?

Admittedly I've been feeling pretty bummed about the short days, temperature drop and being cooped up indoors.

"During the colder, darker winter months, it's not uncommon for some people to find they struggle for motivation and their mood is a bit flatter," says Grant Blashki, Beyond Blue's lead clinical adviser.

Dr Blashki says this is often referred to as the "winter blues".

"A smaller proportion of people find this extends into a more prolonged and regular feeling that we call 'seasonal affective disorder' (SAD)."

I also wanted to know: if you have darker skin, are you more prone to getting SAD in winter, or are other factors at play? So I spoke to mental health experts to find out.

What is SAD?

Professor Greg Murray, director of the Centre for Mental Health at Swinburne University, describes SAD as a variant of clinical depression, where someone has "recurrent depressive episodes" in winter.

"We would consider them to have a diagnosis of the winter pattern depression which some people call SAD."

While it's more common in cold climate areas in the northern hemisphere, it can impact people living in Australia, too.

Although it's rare — affecting "about one in 300" Australians, Professor Murray says.

Professor Ian Hickie, co-director of health and policy at the University of Sydney's Brain and Mind Centre, says it's a "hibernation-like condition".

"In a sense [it's] something we probably share and have in common with bears and other animals that do hibernate," he says.

This can result in "low energy, [gaining] weight and feeling terrible until the spring comes".

Why do we get SAD?

"There is more research that needs to be done on SAD, but the most supported theory is that reduced exposure to sunlight is the primary cause," Dr Blashki explains.

I asked Professor Murray if people with darker skin are more likely to develop it.

He says there's no clear link.

Professor Hickie agrees, saying SAD doesn't have anything to do with skin colour, but rather it's about light exposure.

"It's actually not to do with what comes through your skin but what comes through your eyes," he says.

"Sitting at the back of your eyes is the regulator of our body clock, a thing called the 'suprachiasmatic nucleus' or SCN. That responds to light signals through your eyes and that's the thing that sets your body clock."

And disturbances in the body clock, in this case caused by changes to the amount of light reaching our SCN, can lead to changes in mood, says Professor Hickie.

These body clock changes, he explains, are associated with the onset of depressive disorders like SAD.

When does the blues turn into SAD?

Professor Murray says it depends on the "severity and functional impact".

"It's to do with how much this is impacting your life," he says.

"So, thinking about the functional impact of the change in mood is what distinguishes ordinary lowly mood from clinical depression.

"I always encourage people to ask themselves questions like: 'Am I coping with this OK?' and 'Is this causing me clinical and significant distress?'"

According to the American Psychiatric Association, people with SAD experience mood changes and symptoms similar to depression.

Professor Murray recommends the Beyond Blue website to canvass symptoms, which include: lacking energy, changes in sleeping or eating patterns, and a loss of pleasure in things you might enjoy.

You can also talk to your GP about your symptoms and treatment.

"People with SAD, or with other types of depression, benefit from the same treatment like bright light treatment, psychological therapy and antidepressants."

What about vitamin D?

Another concern in winter, particularly for darker-skinned people, is getting enough vitamin D when the days are shorter.

"People with darker skin tend to have low vitamin D," says Osanda Wijeratne, practising GP and clinical service director for HealthDirect.

That's because they have more melanin, which can soak up ultraviolet and prevent it being used to make vitamin D.

"Darker skin tends to let less of that [ultraviolet] light through, and that reaction to activate vitamin D occurs less during winter," Dr Wijeratne says.

If you want to check your vitamin D levels, you can consult your GP.

Dr Wijeratne suggests considering supplements to get your vitamin D level up, in consultation with your GP — but says nothing beats regular exercise and getting outdoors.

Tips on getting enough sunlight in winter                       

Dr Blashki recommends using a calendar to keep a routine.

"Start with some small manageable exercises for the day, stock up the pantry with healthy foods, tee up regular catch-ups with friends or family — even if that's just online at the moment," he says.

"Make a good effort to get some sun on your face."

Professor Hickie says the timing of sunlight matters.

"In winter months when the day is shorter, get sunlight in the morning and then again in the afternoon to tell your brain which is the light period of the day.

Professor Hickie explains this is because our internal body clock (aka 'circadian rhythm') is controlled by light exposure. It tells us when to wake and when to sleep.

"It's determined by the amount of sunlight during the day and (how) much artificial light at night.

"Sunlight exposure and regulation of the clock doesn't just drive mood, it drives physical activity and eating behaviour. It's a whole physiological set of components."

But regardless of your skin tone, it's important to try to minimise your exposure to UV radiation.

Cancer Council recommends wearing sun protection, including sunscreen, outdoors when the UV Index is above three. When the UV Index falls below three, they say to "spend time outdoors in the middle of the day with some skin uncovered" to boost vitamin D levels.

Dr Blashki also recommends keeping a good routine before you go to bed — bearing in mind you won't always get the balance right.

"Switch off the technology and phones during the night to get some sleep.

"Be gentle with yourself and recognise that you'll have some good and bad days."

This is general information only. For detailed personal advice, you should see a qualified medical practitioner who knows your medical history.