Winter is coming.

No, really, if you live in the Northern Hemisphere, the winter solstice, the shortest day of the year, is this Saturday December 21st.

It marks the time when the northern half of the globe is farthest away from the warm glowing embrace of the sun.

According to astronomy blog EarthSky, the solstice should take place at 12:11 pm ET. After this time, the northern half of the earth should slowly tilt back towards the sun until the summer equinox in June.

If you live in the southern hemisphere, you're celebrating the summer solstice and you can totally give us a call and we'll be right over for a picnic.

The solstice has been noted as an important time throughout human history, and many cultures mark the shortest day (or longest night of the year). The Romans had the feast of Saturnalia, pre-Christian or pagan Europeans celebrated a festival called Yule. Both celebrations helped shape Christmas traditions.

The Chinese celebrate Dongzhi, a day where traditional foods are eaten and families gather to celebrate the solstice.

Other than the cold and bad weather (it is winter in Canada, after all), the short days and lack of sunlight are probably the biggest complaints about the winter months.

Here are 10 things you need to know about Seasonal Affective Disorder: (Story continues after slideshow)

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  • It's New

    Seasonal affective disorder (SAD) is officially new: Seasons have always existed, of course, but SAD was only officially recognized as a disorder in the 1980s. That means that awareness of its seriousness — or that it even exists — is still limited.

  • Some People Get The Less Serious Form

    Some people get a less serious form: Ever heard of the winter blues? <a href="http://www.canadianliving.com/health/mind_and_spirit/7_creative_ways_to_shake_off_the_winter_blues.php" target="_blank">It's a mild form of SAD </a>that can interfere with everyday life, but is different from SAD in that its effects are less debilitating. It's thought that the winter blues may affect up to 15 per cent of the population.

  • It Can Hit You In Warmer Months

    There is such a thing as summer SAD too: It's rarer, but <a href="http://www.webmd.com/depression/summer-depression" target="_blank">summer depression</a> is another milder form of SAD. Those affected usually start to experience symptoms like poor appetite, weight loss, and sleep disturbances in late spring or early summer.

  • It's Not Known What Causes SAD

    The cause of seasonal affective disorder is not yet known. It's believed that it's related to our internal biological clocks, which <a href="http://www.nigms.nih.gov/Education/Factsheet_CircadianRhythms.htm" target="_blank">regulate our circadian rhythms</a>. Some experts think that the differences in light and the length of the day in the winter months affect our circadian rhythms, which then affects our mood. Other research indicates that our neurotransmitters — which regulate sleep, mood, and appetite —may get messed up when someone is suffering from SAD.

  • The Symptoms Can Look Like Something Else

    The symptoms of SAD resemble those of other mental illnesses, like depression and bipolar disorder, and include changes in appetite, intense carb and sugar cravings, weight gain, reduced energy, fatigue, oversleeping, anxiety and sadness, and avoidance of social situations.

  • More Common In Younger Adults

    SAD tends to start appearing in people older than 20, and the risk decreases after the age of 50. However, it can also affect children and teens, and it tends to run in families where other members have experienced depression.

  • More Women Are SAD

    Women are more likely than men to suffer from SAD, but it's not known why. The Mood Disorders Association of Ontario reports that women are up to <a href="http://www.mooddisorders.ca/faq/seasonal-affective-disorder-sad" target="_blank">eight times as likely as men to have SAD</a>.

  • Some Countries Are Harder Hit

    There is some research indicating that seasonal affective disorder is <a href="http://mylittlenorway.com/2008/12/how-to-survive-the-dark-winters/" target="_blank">more common in countries further north</a>, which have shorter winter days or extended periods with very little light at all, in some very northern areas. Shift workers, and workers who don't experience much natural daylight at work and/or home, may also be affected.

  • You Might Want To Book A Vacation

    People who experience the winter blues or SAD may find some relief by heading south. A trip to a warmer destination with longer daylight hours might help you get through the colder months of the year by providing temporary relief.

  • There Is Help Available

    There is help available: If you're experiencing symptoms that are interfering with your day-to-day life, and especially if you are experiencing thoughts of self harm or suicide. MDOA reports that research showed that <a href="http://www.mayoclinic.com/health/light-therapy/MY00195" target="_blank">light therapy with special lamps</a> had an antidepressant effect in 70 per cent of SAD sufferers. Other <a href="http://www.mooddisorders.ca/faq/seasonal-affective-disorder-sad" target="_blank">treatment options include getting more exposure to daylight</a>, exercising, medication, maintaining a healthy diet, and counselling or therapy.

To combat the nasty side of winter, it's alway helpful to think of the positives, so here are some tips for staying energized during the winter months.

And if winter gets to be too much, then remember beaches, sun and warm weather are just a short flight away.

Happy winter solstice!

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