The importance of vitamin D
Vitamin D, though usually regarded as a nutrient, is also classified as a prohormone1 – this means that it’s a substance that your body can convert into a hormone. Vitamin D is important for a number of bodily functions; it helps to support your immune system and it’s vital for the absorption of calcium, promoting strong and healthy bones.
There are vitamin D receptors all over your body, including your immune cells and the part of your brain responsible for regulating your sleep cycle. However, what most people don’t realise is that there are different forms of vitamin D – vitamin D2 and vitamin D3.
The main difference between these two forms seems to be their sources. Vitamin D3, which is arguably the most effective form for raising your overall levels of vitamin D, is synthesised from sunlight and only found in animal-derived food products such as oily fish. Vitamin D2 on the other hand, is often used to fortify foods and is found mainly in plant-based foods such as mushrooms.
Unfortunately, vitamin D deficiencies are extremely common in the UK. As I’ve mentioned, vitamin D3 is mainly produced from sunlight and, if you happen to be enjoying the bleak autumn weather here in the UK, then I’m sure you’re already aware that, with the days growing shorter, your chances of soaking up the sun are rapidly diminishing.
Can low levels of vitamin D affect your sleep?
Vitamin D deficiency in the UK is a real problem and Public Health England has even recommended that the public seriously consider taking a supplement during the winter months.2 Low levels of this nutrient can be associated with a variety of symptoms, some of which are definitely capable of impacting your sleep indirectly. Below are just a few of the more common side effects of not getting enough of the ‘sunshine’ vitamin:
As you can see that’s quite the list of problems that low levels of vitamin D are responsible for. Certainly, if you’re catching colds, suffering from achy joints or mood problems, then it isn’t too far of a stretch to say that your sleep will be impacted.
However, so far this link between low levels of vitamin D and poor sleep has been observational but more recently, a study has emerged that seems to have given more credence to the idea that vitamin D can influence sleep quality.
The study, which involved 3048 male participants over the of 68, measured both vitamin D serum levels and sleep, recording total sleep time, sleep efficiency, wake time and disturbances. Out these 3048 participants, around 16% already had low levels of vitamin D. The results reveal that low vitamin D increased the likelihood of experiencing insufficient sleep and were linked to lower sleep efficiency scores.3
What separates this study from other similar trials in the past is that this study was far more impartial in its approach and measured the results using survey data and objective tools. Of course, that’s not to say it doesn’t have its limitations – it was looking at a very specific age range and gender – but it is promising and it’s hoped that it will lead to wider study in this area.
Do vitamin D supplements help to improve sleep?
Okay, so we’ve established as far as we can that there is a link between low levels of vitamin D and sleep. It therefore makes sense that most people might jump to the conclusion that, if low levels of vitamin D are the problem, then surely taking a supplement to increase your levels of vitamin D will help?
One small double-blind trial conducted in Iran seems to suggest that supplementing with vitamin D may help sufferers. The study involved 93 people between the ages of 20 and 50 and volunteers were assessed using the Pittsburgh Sleep Quality Index (PSQI), a questionnaire that measures sleep quality and disturbances.4
Those in the vitamin D group received an extremely high dose of 50,000 IU vitamin D3 supplement, with one dose every two weeks, working out at around 3571IU a day. At the end of the study, compared to the placebo group, the participants taking vitamin D3 spent longer asleep and it took them less time to fall asleep too.
While these results are positive, it’s important to remember that this was a very small study and the dose given to most participants is far too high considering that most guidelines recommend taking no more than 600-1000IU of vitamin D3 a day!
What can you take away from these studies?
These studies do reveal that there are positive signs that taking a vitamin D3 supplement could help to support your sleep cycles and certainly, during the darker winter months, it might be a good idea for other reasons too! However, it’s important to realise that these preliminary studies are just that, preliminary. Wider research into this area is still needed and, in the meantime, if you do decide to try a vitamin D supplement, it’s important you opt for the right one.
In her blog, ‘Are you getting too much vitamin D?’ our Nutritionist Emma discusses the dangers of vitamin D toxicity. The problem is that people often assume that more means better and this isn’t always the case. Too much vitamin D might be just as detrimental to your sleep patterns as too little – you need to get the right balance.
Many of the vitamin supplements available in supermarkets and health food stores don’t seem to implement this idea though and offer supplements that contain far, far too much vitamin D. Remember, Public Health England are recommending 10mcg supplements during the winter months! Our Balance Mineral Drink provides 100% of your NRV of vitamin D3 and helps to fight fatigue so it might be a nice addition to your daily routine. During the warmer summer months, supplementing might not be so necessary so try to focus on getting the vitamin D you need from sun exposure and your diet.