By Michael Breus, PhD, ABSM
Ever feel a creepy, crawly feeling in your legs when you’re stretched out in bed at night? The kind of odd, tingling sensation that makes you need to shake your limbs, or jump out of bed to move your legs? If so, you may be one of the estimated 10% of Americans who suffer from restless leg syndrome.
Restless leg syndrome (RLS) is a sleep disorder that causes tingling, twitching, and crawling sensation in the legs. These sensations usually occur around the time of sleep: in the evening or when a person is lying down for extended periods of time. These unpleasant sensations make it very difficult to lay still—people with RLS feel a powerful urge to move in order to alleviate those creepy, crawly feelings. RLS can be extremely disruptive to sleep, making it difficult to fall asleep and to stay asleep.
Science has made real progress in recent years in its basic understanding of restless leg syndrome. It wasn’t long ago that there was debate about whether RLS was even a “real” disorder. Restless leg syndrome is now recognized as both a sleep disorder and a neurological disorder. Despite this progress, RLS still remains something of a mystery condition. We don’t know what causes RLS, though studies have shown there may be a strong genetic component. Restless leg syndrome has been associated with a number of other health conditions—including cardiovascular diseases and depression.
A trio of new studies, each conducted by groups of researchers at Boston’s Brigham and Women’s Hospital and Harvard Medical School has explored the relationship between RLS and three other health conditions: hypertension, coronary heart disease, and depression. All three studies relied on data from the Nurses’ Health Study, a decades-long project that collects and analyzes information about women’s health, using female nurses as subjects.
In a study of RLS and hypertension, researchers investigated a possible relationship between restless leg syndrome and high blood pressure in middle-aged women. Using subjects from the Nurses’ Health Study, researchers included 64,544 women between the ages of 41-58. All the women included had been given a probable diagnosis of RLS, and were experiencing symptoms at least five times per month. Women with certain conditions, including arthritis and diabetes, were excluded, since aspects of both of these conditions can appear similar to restless leg syndrome.
Using information collected via questionnaire and adjusting for other medical and lifestyle factors that could affect hypertension, including age, weight, physical activity, tobacco, and alcohol use, they found:
- Women with restless leg syndrome were more likely to have hypertension than those without RLS
- The more severe the RLS, the more the chances a woman also had high blood pressure: women who reported having RLS symptoms 15 or more times in a month were significantly more likely to have hypertension
- RLS was associated with increases in both systolic and diastolic pressures
Researchers cautioned that this study does not demonstrate a direct, causal link between restless leg syndrome and hypertension. Rather, it shows an association between the two, which warrants additional investigation.
In another study, researchers examined a possible link between RLS and coronary heart disease. In particular, researchers considered how the duration of RLS symptoms over time might relate to incidence of heart disease. Researchers evaluated information from 70,977 women over a period of 5.6 years. The average age of the women was 67. None of the women included in the study had evidence of coronary heart disease at the study’s outset. They found:
- Women who had restless leg syndrome when the study began had a greater risk of developing coronary heart disease during the observation period than those who did not begin the study with RLS
- The risk of developing heart disease appeared to be influenced by the duration of restless leg syndrome. Researchers found that women who had experienced RLS symptoms for three years or more had a higher risk of developing coronary heart disease than women without symptoms, or those who had experienced RLS symptoms for a shorter period of time
As with hypertension, previous studies have shown an association between restless leg syndrome and coronary heart disease. This study bolsters evidence of that relationship. But as researchers themselves noted in discussing these results, the details of the relationship between RLS and heart disease isn’t clear. We don’t yet know the path by which RLS may influence the development of coronary problems, or vice versa. Is it the lack of sleep that accompanies RLS? Does it have to do with the hypertension that is also associated with restless leg?
In a third study of health problems associated with RLS, researchers looked at a possible link between restless leg syndrome and depression. Again using participants from the Nurses Health Study, researchers followed 56,399 women for approximately six years. The women’s average age was 68, and none had symptoms of depression at the start of the study. During the six-year observation period, 1268 women developed clinical depression. Researchers found:
- Women who had RLS at the study’s outset were more likely to develop depression than those who did not have RLS
- Women with RLS scored higher on two standard depression tests than women without RLS
Other studies have indicated an elevated risk of depression for people with restless leg syndrome—as much as 2 to 4 times the level of risk than for those without the sleep disorder. Complicating this picture, it is believed that some anti-depressant medications may exacerbate RLS symptoms.
All three of these recent RLS studies were conducted with women subjects only. Additional research on these subjects will need to continue to explore these RLS-linked health problems with both men and women.
Restless leg syndrome is thought to be dramatically under-diagnosed. Once identified, however, there are a number of effective treatment options, including:
Physical therapies: bath, massage, and exercise
Lifestyle changes: reducing or eliminating the consumption of alcohol, caffeine, and tobacco
Prescription medications: in cases of more serious RLS, or RLS that doesn’t respond to other therapies, there are several medications that can treat the symptoms of this disorder
These studies provide a potent reminder that sleep disorders such as RLS have complicated and consequential links across the spectrum of mental and physical heath. While we’re working to learn more about the causes of RLS, and relationship between restless leg syndrome to other health problems, we also need to be working harder to make sure those who suffer from this disorder don’t go un-diagnosed and un-treated.
Michael J. Breus, PhD
The Sleep Doctor™