light therapy SAD syndrome

In the northern hemisphere, the temperatures have dropped, the rain is falling, the wind is howling and the nights are drawing in - all  clear indications that we are approaching SAD season.  Seasonal Affective Disorder (SAD) generally occurs between December and February, with symptoms improving in the spring when the days start to get longer and brighter again. Three times more women than men get SAD, and it is more common in people aged 18 - 30, although the problem is increasing in young adolescents side by side with the increase in non seasonal depression.

Theories abound on what seasonal affective disorder actually is and what causes it. Is it a human form of hibernation? Are we taking to our beds and slowing down like a dormouse or tortoise, hoping that the winter will pass us by.  Many other animals exhibit hibernation-like behaviour without actually going the whole way, like bears and squirrels.  Many SAD symptoms do seem to  tie in with hibernation behaviour which revolves around economising on expenditure of energy during a time when food and resources are limited. For example, symptoms such as overeating and craving carbohydrates is in line with creating body reserves for the winter. Lack of energy, difficulty waking up and difficulty concentrating on or completing tasks all conserve physical and mental energy . Withdrawal from social activities and decreased sex drive are effectively measures to prevent  pregnancy at a time when food resources are low.

Why do some people suffer from it and others not?  Other theories suggest that there is a genetic link back to the universal African Eve. The early humans descended from the African Eve were used to an equatorial climate with no seasons and 12 hours of daylight and 12 hours of night. As they migrated out of the equatorial zone some adapted well and genes related to circadian rhythm spontaneously modified, whereas others may not have  inherited the modifications or simply did  not adapt.

Whatever the historical reason, it is universally accepted that lack of light aggravates or causes Seasonal Affective Disorder.  New theories also point to a lack of the sunshine vitamin, vitamin D.  Both of these ideas fit in with the fact that in the northern hemisphere Seasonal Affective Disorder is more common at higher latitudes. The exception to this being Icelanders, Japanese and Canadians of Icelandic descent who have lower than expected levels of SAD. These exceptions have been put down to the fact that these populations have a diet that is high in fish, hence high intake of fish oils.

Light therapy is a standard treatment for seasonal affective disorder however a new study has taken this to a new level.  The study published this month in BMC psychiatry looked at the effect of light passed through the ear canals on the depressive symptoms of SAD. Over a four week period, volunteers were given 12 min doses of different light intensity in the ear canals and the effect on symptoms of depression was measured using a standard rating scale. All of the patients had reduced symptoms of depression and a quarter of the patients had mild side effects such as headache, nausea and some sleep problems. The group concludes that the transcranial light treatment results are as good as more conventional light treatments and reduce depression and anxiety in patients with SAD.

There are many different treatments besides conventional medicine and Light therapy to treat SAD.  Mind body therapies, talk therapies, lifestyle changes, nutrition and some herbal remedies have all been shown to improve symptoms. Take a look at the  Patient QI Seasonal Affective Disorder treatment strategy for further information.


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