The 3 most common causes of restless leg syndrome

Author: Dr. Michelle Durkin on 16 February 2021

Restless leg syndrome (RLS). That uncomfortable sensation in your legs that creates an irresistible urge to move them. And an annoying symptom that disrupts your ability to fall asleep or return to sleep on waking at night.

So what is causing these aching, throbbing, pulling, itching, crawling, or creeping sensations that can be so disruptive for sleeping or even just resting and watching a movie?

Here are three common causes you should be aware of:

1. Low intracellular magnesium - low magnesium is probably one of the most well known causes of RLS. Magnesium is needed in over 200 enzymatic reactions in the body and it can easily be depleted. It is one of the best minerals to help relax the nervous system and when you are under higher stress it gets depleted faster. It is this relaxation effect that helps with RLS (and sleep!). The best blood test to know if your magnesium is low is called Red blood cell magnesium. This is not the same test as serum magnesium. In my experience your number should be within the reference range given by the lab.

2. Suboptimal iron levels - iron is needed to carry oxygen around to our tissues, therefore when we don't have enough iron, our oxygen carrying capacity is compromised. A small, but significant enough decrease of oxygen to our lower legs could cause symptoms of RLS. The best blood test to know if your iron is optimal is called Ferritin. In my experience if your number is < 25 you could have a problem.

3. High or high normal blood sugar - that's right, RLS could be a warning sign of insulin resistance or pre-diabetes. When blood sugars are higher glycosylation of hemoglobin occurs. Visualize glycosylated hemoglobin as a sphere with little spikes on it. Then think of that spiked sphere travelling along a tube (your blood vessel). That could cause some irritation. Hence symptoms like itching, crawling & creeping in the small blood vessels in the legs. The best blood test to know if your blood sugars are starting to run too high is called Hemoglobin A1C. In my experience if your number is > 5.5 you could start having symptoms.

Now I would love to hear from you! Is restless legs something that you suffer from? Leave a comment below and I'll be back next week with another edition of Doctor as Teacher Tuesday!

4 Replies to “The 3 most common causes of restless leg syndrome”


I suffer from RLS from time to time. I had figured that high blood sugar levels can be one of the causes, but I didn’t know about the importance of having the right levels of magnesium and iron in the system.
Do you think it is important to get the tests for the magnesium and iron levels and how do you get tested?

Dr Michelle Durkin ND

Hi Sylvia,
Yes, both magnesium and ferritin (iron) are simple blood tests.


Hello Dr Durkin, this article on Magnesium has me wondering of other issues (I have suffered from RLS) that this deficiency may cause.
If a “blood chemistry test” excluding blood gases & glucose, reads “MG” would this be serum magnesium or red blood cell magnesium test?

Thank god we have an alternative to allopathic doctoring in this community. I firmly believe in treating the root cause and not just it’s symptom(s).

Dr Michelle Durkin ND

Hi Larry,

The test you would have had done would be serum magnesium. The other would be listed as rbc Mg.

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