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Why Winter Makes You SAD: Seasonal Affective Disorder Explained

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Channel: The Royal Institution
Categories: Biology   |   Health   |   Psychology   |   Science  
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Ever wondered what Seasonal Affective Disorder actually is? Or if it’s even a real thing? What causes it? Kate tackles sudden changes in hormones and light intensity in an attempt to explain why winter makes you SAD.
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It’s perfectly natural for people to unwind and perk up at the beginning of summer as the appearance of the sun marks the end of a dark and gloomy winter. However for some people changing seasons can have such significant impacts on their mood that they are said to be suffering from Seasonal Affective Disorder, otherwise known as SAD.

SAD involves the effects of depression either developing or worsening during the wintertime and it is believed to be in part stimulated by the change in light intensity as the number of daylight hours decreases in the colder months. This is due to the change in the environment causing an imbalance in the hormones that control your mood. Different people react differently to this change, hence the small amount of people that suffer from SAD.

It’s this could be partly due to our ancestors hibernating in winter months. However, not to worry; if the effects of the disorder are really too much, just move to Arizona, the sunniest place in the world.

This film is part of our series that provides the blueprint for a scientifically perfect summer. From sweating to hay fever, insects to jet lag, Kate Mulcahy helps you hack summer to engineer the perfect season. Taking a different topic each Thursday, the videos will gradually build up an equation for summer perfection; a summer survival guide certified by science.
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Kurlansik, S.L. and Ibay, A. D. (2013) Seasonal Affective Disorder. Indian Journal of Clinical Practice. 24(7): 607-610
Revell, V.L. et al (2006) Advancing Human Circadian Rhythms with Afternoon Melatonin and Morning Intermittent Bright Light. The Journal of Clinical Endocrinology & Metabolism 91(1): 54-59
Wehr, T.A. (1997) Melatonin and Seasonal Rhythms. J Biol Rhythms 12: 518-527

Vivacity by Kevin MacLeod (
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Mining by Moonlight by Kevin MacLeod (
Licensed under Creative Commons: By Attribution 3.0

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