A recent study found that restless legs
syndrome is more frequent and severe in
vitamin D deficient individuals. Additionally,
vitamin D deficiency was associated with poor
Restless legs syndrome is a chronic, progressive
neurological disorder characterized by an
uncontrollable urge to move one’s legs, usually
due to leg discomfort. Moving temporarily
relieves the discomfort. RLS often disrupts
sleep; about 20 percent of patients with RLS
have sleep disorders.
The cause of RLS is typically unknown.
However, researchers believe an imbalance of
dopamine likely plays a role. Dopamine is a
brain chemical that sends messages to control
muscle movement. The most commonly used
treatment for RLS is dopamine agonists, which
are chemicals that bind to receptors and elicit
the production of dopamine.
Research has shown that vitamin D increases
the levels of dopamine in the brain and
protects the brain from toxins that can cause
an imbalance of dopamine levels. This led
researchers to suspect that vitamin D may help
treat RLS. One pilot study found that vitamin D
supplementation improved the severity of RLS.
However, this study only included 12 patients.
Researchers recently conducted a study in 102
patients to assess the link between vitamin
D deficiency, the frequency and symptom
severity of RLS, and sleep quality in vitamin
D deficiency. The researchers evaluated these
outcomes in two different groups: those who
were vitamin D deficient (levels less than
20 ng/ml) and those who were vitamin D
sufficient (levels greater than or equal to
The researchers diagnosed RLS based on the
International RLS Study Group diagnostic
criteria. Individuals were diagnosed with RLS
if the patient experienced all of the following
symptoms: urge to move the legs, onset of
exacerbation with rest, relief with movement
and worsened symptoms in the evening.
The severity of RLS was assessed with the
International RLS Study Group Symptom
Severity Scale. This scale asks questions about
the typical symptoms of RLS, each graded 0-4.
Higher points indicate a higher severity of the
disease. The Pittsburgh Sleep Quality Index
(PSQI) was used to evaluate sleep quality. The
PSQI scores the quality and amount of sleep,
and the presence and severity of sleep disorders,
with a higher score representing worse sleep
The incidence and severity of RLS along with
sleep quality were compared between the two
groups. Here is what the researchers found:
• The vitamin D deficient group had a
significantly higher incidence of RLS
compared to the vitamin D sufficient group
(p = 0.034).
• The Pittsburgh sleep quality index points
were significantly worse in the vitamin D
deficient group compared to the vitamin D
sufficient group (p < 0.05).
• No significant difference was observed in
symptom severity between the two groups.
The researchers concluded, “[...] the results of
this study demonstrated a relationship between
vitamin D and RLS and sleep problems.”
The main limitation of this study is that it
does not prove causation. The study does not
conclude that vitamin D supplementation
improves RLS. Also, the study was not
prospective. Large randomized controlled
trials need to be conducted in order to increase
the understanding of the effects of vitamin D
supplementation on RLS.
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