Why is winter so SAD?
Did you know that, as of now, no one has been able to pin down the exact cause of SAD, or Seasonal Affective Disorder? This understandably presents numerous problems when it comes to treating the condition, but, for now at least, let’s focus on what we do know: the symptoms of SAD appear to be linked to how our body responds to light.
This explains why the condition appears in winter at least – in the Northern hemisphere, between the months of November and February, most of us go to work and come home in darkness and our exposure to sunlight is considerably limited. Why does sunlight affect our moods though? Well, here the answer lies in our hormones. You see sunlight isn’t just a source of warmth for human beings, our bodies have evolved to respond to light and it influences the production of certain hormones and chemicals.
Take the sleep hormone melatonin for example, when your eyes perceive sunlight they send a message to your brain which triggers the release of cortisol, a steroid hormone, and reduces your levels of melatonin to make you feel more awake and invigorated during the daylight hours. Sunlight also plays a valuable role when it comes to serotonin, the happy hormone. It’s believed that sunlight can help to increase our production of serotonin whereas less exposure to sunlight can have a knock-on effect, lowering our levels of serotonin and thus influencing our mood.
So, as you can see, it becomes easy to draw a correlation between the symptoms of SAD and our limited exposure to sunlight – elevated levels of melatonin and low levels of serotonin could easily contribute to feelings of lethargy, apathy and low mood but our exposure to sunlight also influences our production of another well-known hormone – vitamin D.
Is vitamin D good for SAD?
Vitamin D is primarily known as a nutrient, but it’s also classified as a hormone too!1 This makes it pretty unique; especially when you consider that, unlike other vitamins and minerals, our primary source of vitamin D is sunlight. Almost immediately this creates a connection between having low levels of vitamin D and SAD – both occur when our exposure to sunlight is minimal. In fact, here in the UK, it’s thought that as many as 1 in 5 of us could be suffering from low levels of vitamin D – a worrying statistic, especially when you consider the symptoms of vitamin D deficiency.2
The symptoms of vitamin D deficiency
- Fatigue
- Poor immunity
- Joint pain
- Muscle pain
- Low mood
- Poor bone density
These symptoms are unpleasant to experience and many, such as joint pain and poor bone density, are connected to vitamin D’s role in regulating our absorption of calcium. For now, though, let’s look at two symptoms that do have some crossover with SAD – fatigue and low mood. There’s actually quite a lot of evidence linking low vitamin D levels with low mood – a 2013 meta-analysis found that participants who suffer from mood disorders such as depression often had low levels of vitamin D.3
This is interesting as SAD is sometimes known as ‘winter depression’ and is recognised as a type of depression by the NHS.4 How vitamin D influences the mood isn’t well understood but studies have found that there are vitamin D receptors in the brain, particularly areas of the brain associated with depression.5 This has led many scientists to theorise that vitamin D could play a role in influencing certain hormones such as serotonin and dopamine, low levels of which are also linked to SAD.
So, just to clarify, SAD and low levels of vitamin D share quite a lot in common – both are influenced by a lack of sunlight, both appear to have an impact on our mood and both are linked to mood hormones such as serotonin and dopamine. It wouldn’t be too much of a stretch to suggest that many with SAD also suffer from low levels of vitamin D but, as of yet, there’s no conclusive evidence pinpointing vitamin D’s role in SAD.
One study conducted by the University of Georgia stated that a link between vitamin D deficiency and depression is ‘logical’ based on their findings. This study also hypotheses that, rather than being a side-effect of SAD, vitamin D deficiency could be an underlying cause. This is based on the 8 week lag period between the peak in intensity of UV radiation (sunlight) and the onset of SAD which appears to be linked with how long it takes for UV radiation to be processed into vitamin D.6
Once again though, this evidence is based on observation. SAD sufferers might also experience low vitamin D levels due to their sedentary lifestyle rather than low vitamin D levels being a primary cause of SAD. Or, perhaps as the researchers at the University of Georgia suggest, low levels of vitamin D could be creating an imbalance in serotonin and dopamine. The answer is up for debate as is the efficiency of using vitamin D supplements to treat SAD symptoms.
Do vitamin D supplements treat the symptoms of SAD?
When it comes to treating SAD, vitamin D supplements are becoming a popular option but, given the lack of conclusive evidence that low levels of vitamin D actually causes SAD, how effective are these supplements? Actually, the results are quite mixed!
A small Danish study examining 34 participants found that vitamin D supplementation produced no significant results when it came to treating SAD symptoms.7 Of course, this study does have limitations given its small scope, plus it’s worth noting that none of the participants actually reported having low vitamin D levels to begin with. In other studies where volunteers have had low vitamin D levels, supplements have produced more positive results – one study looking at adults with vitamin D deficiencies found their depressive symptoms improved after taking high strength vitamin D supplements for two months.8
So, perhaps for vitamin D supplementation to influence your mood, you must already have low levels of the nutrient. As with everything concerning SAD, there isn’t a clear answer but it is worth bearing in mind that the government has recently changed their guidelines concerning our vitamin D intake. Public Health England is now recommending that all of us consider a 10mcg vitamin D supplement during the winter months to ward off the risk of deficiency, with high risk groups possibly needing to consider a slightly stronger dose.9
No matter whether vitamin D can help to ease SAD symptoms or not, there is no doubt that having low levels of vitamin D can impact your mood which, in addition to SAD, may exacerbate your symptoms. That’s why I recommend a gentle vitamin D supplement during the winter months such as our Balance Mineral Drink.
My Top Tip: Balance Mineral Drink contains a combination of calcium, magnesium, vitamin D and potassium to help replenish any lost electroyltes and to keep you feeling energised throughout the day..
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Okay, so vitamin D may be useful for SAD symptoms in instances where a deficiency is present but the question remains – what can you do to ease SAD symptoms?
How do you beat SAD?
When it comes to tackling the symptoms of SAD, one of the best things you can do is actually one of the things you feel like doing the least – getting out in the fresh air!
Getting outdoors maximises your exposure to sunlight which not only boosts your production of vitamin D, it helps to stimulate the release of cortisol making you feel more awake and energised. A brisk 20 minute walk in the winter sun can make all the difference by increasing your production of dopamine whilst also reducing anxiety and low mood.
Even if the weather is miserable though, that’s no excuse to sit indoors – some gentle exercise can really go a long way so get up off the couch and keep moving. Arrange to go swimming with a friend or join a yoga class – these are low-impact forms of exercise that should be kind on your body, plus the latter also teaches deep breathing techniques that can be useful for combatting stress and anxiety.
If you want more tips on how to beat SAD, I really recommend reading my blog ‘5 natural 
ways to prevent SAD’ and, if you want some insight into how your diet can help, ‘8 foods to fight the winter blues’ might also be a useful addition to your reading list. If you feel you need further assistance in coping with your symptoms though, you could consider a herbal remedy like St John’s Wort Hyperiforce which can help to gently relieve slight symptoms of low mood and anxiety. Just remember to read the product information leaflet carefully to make sure it isn’t contraindicated with any of the medications you are taking.
Finally, if you are well and truly struggling with your SAD symptoms it’s really important that you speak to your doctor. SAD is recognised as a mental health disorder by the NHS so don’t worry, you will be taken seriously and your doctor should be able to guide you through other treatment options.
1https://www.hormone.org/hormones-and-health/hormones/vitamin-d
2https://www.nutrition.org.uk/nutritioninthenews/new-reports/983-newvitamind.html
3https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry
4https://www.nhs.uk/conditions/seasonal-affective-disorder-sad/
5https://www.ncbi.nlm.nih.gov/pubmed/15589699
6https://www.medicalnewstoday.com/articles/286496.php
7https://bmcresnotes.biomedcentral.com/articles/10.1186/1756-0500-7-528
8https://www.ncbi.nlm.nih.gov/pmc/articles/PMC506781/
9https://www.gov.uk/government/news/phe-publishes-new-advice-on-vitamin-d
