I Tried Vitamin D To Help Me Sleep. Does It Work?

This year, I’ll be trying sleeping tricks to see whether they actually improve my insomnia. Check back in on this series, Rest Assured, to see how I get on.

Because I have absolutely no trouble falling asleep, I didn’t realise for years that my 3am wakeups actually constituted a form of insomnia (sleep maintenance insomnia, to be precise). 

On average, I wake up in the middle of the night just under five times a week. I only return to sleep about a quarter of those times. 

So, I’ve been trying everything from kiwis to passionflower tea to see whether they have any benefits. Both have stuck, but what about my now months-long habit of taking a daily vitamin D supplement daily? 

Wait, does vitamin D help with sleep? 

Some research suggests it might, yes. 

We know that vitamin D deficiency, which the NHS warns is common in the UK’s gloomy climes from October to about March, appears to be a “forgotten aspect in sleep disorders”. 

It may cause issues with both sleep maintenance (staying asleep, which is my issue) and sleep regulation.

It’s even been linked to obstructive sleep apnoea (OSA), though that’s a bit of a “chicken and egg” scenario – maybe OSA causes vitamin D deficiency, a 2024 paper said, or maybe the lack of vitamin D raises OSA risk.

Either way, a 2022 review and meta-analysis of studies found that vitamin D supplementation seemed to be linked to better sleep quality. 

Another paper said that vitamin D helps to create the sleep-regulating hormone melatonin and seems to help those with conditions like restless leg syndrome and OSA to get better sleep.

So, how did it go? 

In my previous attempts to conquer my insomnia, I gave science-backed “fixes” a go for a week. 

But it can take as long as two to three months for the benefits of vitamin D to kick in (I’ve been taking it for about six months).

I will say that I’ve noticed slight, but not life-changing, benefits to my sleep since then. I keep to a more consistent bedtime, which is important for sleep regulation. 

And I haven’t gotten as ill as I usually do in winter, which may be linked to the vitamin (and, of course, indirectly affects my sleep). 

There are some caveats with vitamin D supplementation, though. Vitamin D3 may do more for our immune system than vitamin D2, and, per the NHS, “Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body (hypercalcaemia).” 

10 micrograms a day (mcg) should be enough for most adults, they add, and we should never supplement more than 100mcg of vitamin D a day.

“From about late March or early April to the end of September, the majority of people should be able to make all the vitamin D they need from sunlight on their skin,” the health service added. 

For the winter months, however, I’ve found it helpful. Sure, I’ve noticed the benefits most in my immune system, but what I think might be a couple of positive sleep-related changes caused by the supplement are welcome too.