What's The Difference Between SAD & Depression? The Two Conditions May Be More Similar Than You Think

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Right now in the UK, it's constantly dark, it's incredibly cold, and that long, sun-drenched summer feels like a lifetime ago. For almost all of us, winter is a miserable time. But these sunless months can have a more severe effect on some people than others. For those suffering from Seasonal Affective Disorder (SAD), the winter can be acutely difficult. But how do you know if you have SAD? And what is the difference between SAD and depression?

The man who is credited with "discovering" SAD, Dr. Norman Rosenthal, actually experienced the condition firsthand, according to U.S. News. Rosenthal, who is the clinical professor of psychiatry at Georgetown University School of Medicine and author of Winter Blues: Everything You Need to Know to Beat Seasonal Affective Disorder, spoke to the news site about his experience coming from sunny South Africa to the U.S. for a psychiatry residency:

“For the first time, I experienced marked seasonal changes in myself,” the professor told U.S. News. “I slowed down, was less productive, felt less creative. When summer came, I wondered what that fuss was all about."

Rosenthal went on to say: “Without my own experience, I would not have been primed to believe in this syndrome, and there still is some skepticism."

The professor explained that people with SAD do in fact have "major depression" (also know as simply "depression" or "clinical depression," according to the U.S. National Institute for Mental Health). "It can be just as severe," he said. "It just happens to be seasonal."

Rosenthal cited a study he did Scandinavian as evidence. According to U.S. News, he found that participants with SAD did in fact display more more symptoms of major depression than those who suffered from the illness non-seasonally.

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On their information page about SAD, the NHS writes that, "[t]he exact cause of SAD isn't fully understood, but it's often linked to reduced exposure to sunlight during the shorter autumn and winter days. The main theory is that a lack of sunlight might stop a part of the brain called the hypothalamus working properly."

The NHS explains that this disruption to the hypothalamus may affect the production of melatonin (the hormone that makes you feel sleepy) and of serotonin (the hormone that affects your mood, appetite and sleep). They state that "a lack of sunlight may lead to lower serotonin levels." The hypothalamus will also affect the body's internal clock (or its "circadian rhythm"), as "your body uses sunlight to time various important functions, such as when you wake up, so lower light levels during the winter may disrupt your body clock and lead to symptoms of SAD."

The NHS lists the following symptoms for SAD:

  • a persistent low mood
  • a loss of pleasure or interest in normal everyday activities
  • irritability
  • feelings of despair, guilt and worthlessness
  • feeling lethargic (lacking in energy) and sleepy during the day
  • sleeping for longer than normal and finding it hard to get up in the morning
  • craving carbohydrates and gaining weight
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When speaking about treatment for the condition, the NHS suggests changes in lifestyle (such as exercise and managing stress), talking therapy, cognitive behavioural therapy or, in some cases, anti-depression medication. The NHS also states: "Some people with SAD find that light therapy can help improve their mood considerably," which involves "sitting by a special lamp called a light box, usually for around 30 minutes to an hour each morning." If you want to buy a light box, there are plenty on Amazon, and John Lewis sells quite a few.

Your GP will know the right cause of action for you, so you should seek their advice if you thin you may be suffering from SAD or any other form of depression.