Seasonal Affective Disorder – SAD – is not the same as the winter blues. So if you think you may be suffering, it’s important to treat it seriously.

Read on and you’ll discover:

• How to identify the difference between the winter blues and the depressive illness known as Seasonal Affective Disorder (SAD)
• The types of exercise that best combat SAD
• Facts about how light therapy and cognitive behavioral therapy affect SAD
• Other activities that can alleviate the stress associated with SAD, including free access to mindfulness meditation sessions.

Seasonal Affective Disorder (SAD) – a form of depressive illness related to the seasons, generally beginning in the fall and continuing throughout the winter – affects around 10 million people in the US and many more worldwide.

But it’s important not to confuse SAD with the plain old winter blues, which everyone experiences at some time or other during the coldest, darkest months. To have genuine SAD, you’ll have experienced symptoms for two years running, including feeling constantly tired, spending longer in bed, increased appetite, lack of motivation and disturbed sleep.

SAD tends to affect adults (especially those aged 18 to 30) more than children or teenagers (although this tends to decline after the age of 50). Women are significantly more likely than men to have SAD, possibly due to evolutionary influences on seasonal reproductive cycles. And it is most prevalent in northern latitudes where daylight hours are fewer.

Common wisdom has it that simple exposure to more sunlight is the answer, as this will provide more vitamin D, but this may not be the total answer. Yes, as this study found, vitamin D deficiency can exacerbate SAD. Vitamin D may be involved in the production of feel-good neurotransmitters serotonin and dopamine, and people who are depressed commonly have low vitamin D levels.

However, it has not been established that low vitamin D levels are the main cause of SAD. Another study found that supplementation of vitamin D did not directly improve symptoms. And in places where winters are particularly long and dark, simply getting outside for some healing rays is not really an option.

What is not in doubt is the value of exercise in combatting any form of stress, anxiety or depression – including SAD. This is especially true if you balance your intense cardio and strength classes with mindfulness-based exercises and activities such as yoga and meditation. According to this research, for example, just 25 minutes of mindfulness meditation can significantly alleviate stress. If you’re new to this, there are now simple-to-use apps containing useful breathing and meditation sessions, some as short as five minutes. You can check out these sessions on Calm, Headspace or for free on LES MILLS On Demand.

If you’re lucky enough to live somewhere you can get outdoors in winter, we now know that spending as little as 20 minutes in nature can lower stress hormone levels and boost mood. You can burn more calories jogging outdoors than on a treadmill (owing to the differences in the terrain and wind resistance). Unfortunately, some modern urban dwellers are spending up to 90 percent of their time indoors – so if all that’s keeping you from getting out more is a busy schedule, it’s probably time to rebalance this in favor of the mental and physical benefits of being in nature.

For those living in genuinely inhospitable places, or who find exercise and a healthy diet aren’t lifting them out of a SAD slump, there are various forms of therapy. Light therapy – which involves sitting or working near a “light therapy box” that emits bright light to mimics natural outdoor light – has been shown to work, as has cognitive therapy.

One study of people being treated for SAD with cognitive behavioral therapy found only seven percent of participants experienced a recurrence of depression, compared to 36.7 percent of people treated with light therapy. The relapse rate was lowest when light therapy and cognitive behavioral therapy were combined (5.5 percent), suggesting a multifaceted approach may be the key to making a noticeable improvement when severe depression strikes.

Anyone who feels they are suffering severely from SAD should, in the first instance, consult their health professional to determine the best treatment options. For the rest of us, getting out in nature and staying active will go a long way to letting a little sunshine into our lives.

Isabella Lovett worked in healthcare before becoming a full-time health and wellness blogger and writer.