People with a problem that causes fidgety legs may have an increased risk of heart disease, a study shows.
Restless leg syndrome (RLS) is a neurological disorder that produces a strong urge to move the legs. It tends to be accompanied by a feeling of tingling or "crawling" under the skin.
Researchers found that RLS leg movements could push up blood pressure to potentially dangerous levels, especially in the elderly.
Periodic leg movements are typically most severe at night, when they can occur every 20 to 40 seconds.
For the study, 10 people with untreated RLS spent the night in a sleep laboratory where scientists monitored their leg movements and blood pressure.
During periodic leg movements, systolic blood pressure rose by an average of 20 points and diastolic pressure by 11 points.
The first reading measures blood pressure with each beat of the heart. The second shows the pressure between beats.
Researcher Dr Paola Lanfranchi, from the University of Montreal in Quebec, Canada, believes long-term sufferers of RLS are at increased risk from changes in their blood pressure.
"The repetitive rise in blood pressure during periodic leg movements could be harmful to the cardiovascular system, especially in severe cases of RLS, the elderly, and those with a long history of the disease.
"Past studies have shown that significant blood pressure changes, as shown in our study, are associated with the development of vascular and heart damage.
"Furthermore, drastic blood pressure surges at night have been associated with a higher rate of stroke in the elderly."
The blood pressure changes increased with age and the length of time people had suffered from RLS.
Co-author Dr Jacques Montplaisir, also from the university, said: "Further studies are needed to clarify and quantify the damaging effects of such changes on the heart and blood vessels and also to determine how medications for RLS may impact this damaging effect."
The findings are published in Neurology, the journal of the American Academy of Neurology.