Restless legs syndrome (RLS) is a chronic disorder characterized by unusual sensations in the limbs relieved with movement. The incidence may be increasing as recent studies show it affects between 7% to 10% of the general population in North America and Europe. However, many of these cases are mild. Sixty percent of cases are familial, but the exact mechanism is unclear except that the neurotransmitter dopamine is involved.
In 2003, the National Institutes of Health listed four major symptoms of RLS:
- An urge to move the limbs with or without unusual limb sensations.
- Improvement with activity. Many patients find relief when moving and the relief continues while they are moving. In more severe RLS this relief of symptoms may not be complete or the symptoms may reappear when the movement ceases.
- Worsening at rest. Patients may describe being the most affected when sitting for a long period of time, such as when traveling in a car or airplane, attending a meeting, or watching a performance. An increased level of mental awareness may help reduce these symptoms.
- Worsening in the evening or night. Patients with mild or moderate RLS show a clear daily rhythm to their symptoms, with an increase in symptoms and restlessness in the evening and into the night.
Is vitamin D involved?
It may be more (not less) common when vitamin D levels are higher, such as the summer. At least there are more internet searches for RLS in the summer.
Also, apparently it is less common among Blacks than Whites, the opposite of what one might expect if vitamin D deficiency was involved.
However, on the other hand, RLS has a latitudinal gradient, the further from the equator, the more common the disorder (R = -.74).
Scientists have also found lower vitamin D levels in people with RLS than controls and that vitamin D levels are directly related to severity, the higher your vitamin D levels the less severe your RLS symptoms.
As this disorder affects millions of people, more research is urgently needed into this field. The evidence vitamin D deficiency is involved is mixed.