According to some recent studies, a sleep disorder involving the legs might occur more frequently in older women and seems to have a link to another more serious disorder — sleep apnea.
Period leg movement during sleep (PLMS) — also known as periodic leg movement disorder (PLM) — means that a person’s leg, ankle, and big toe muscles tend to flex while he/she is sleeping. A similar condition you might have heard of, restless legs syndrome (RLS), occurs while a person is awake; RLS patients usually also suffer from PLMS (but it doesn’t work the other way around).
The disorder does not seem to be all that serious, but it can disrupt your sleep patterns, causing you to be sleepy, less alert, and to have slower mental function during the day. Moreover, it can be a sign of a more serious condition. If you have PLMS, you might not even know it — based on your daytime symptoms, a doctor will have to refer you to a sleep specialist, who will run sleep tests. If you have a partner, he/she is more likely to notice your leg movements during sleep than you are.
A study out of the University of California monitored the sleep patterns and leg movements of 455 women (average age was 83). In an hour of sleep, two-thirds of the subjects were found to have five (or more) uncontrollable leg muscle movements, while just over half had 15 or more. Also, 27% of the women were awakened by PLMS an average of five or more times every hour, and six percent had interrupted sleep 15 or more times in the same period.
The study participants who were found to have PLMS did not sleep well; they awoke more often during the night and did not sleep as much during the third, fourth, and rapid eye movement (REM) stages of sleep.
Note that there are five stages of sleep, with stages three and four being periods of deeper sleep; REM sleep involves dreaming, increased heart rate and breathing, and muscle twitches. Many experts believe REM sleep to be extremely important for maintaining optimum mental function and think that a lack of it for an extended period of time could cause major problems. The cycles repeat over and over again throughout the night.
Since the number of people over 60 years of age with PLMS disorder is pegged at 34%, this study seems to show that women over 80 are more prone to the condition.
In other news, a Kuwait/Canada study showed a link between PLMS disorder and “obstructive sleep apnea.” When a person repeatedly ceases to breathe during sleep, this is called sleep apnea. The term “obstructive” refers to the cause behind the problem: the airway is blocked, usually when the muscles in your throat relax, making the soft tissue at the back of your throat close.
This condition can not only cause sleep disturbances, making a person constantly wake up throughout the night (in addition to keeping his/her partner awake, as loud snoring is usually a side effect), but has also been linked to heart disease, headaches, and memory problems.
The study examined 798 patients who were suspected of having obstructive sleep apnea; out of these, 92% were diagnosed with the sleep-breathing problem, 47% had PLMS, and 44% had both of the disruptive sleep conditions. Of the patients with apnea, half had PLMS. So, this means that there is a connection between apnea and involuntary leg movements during the night.
Exactly how they are related and which condition is a precursor of which is unknown. In addition to apnea, other conditions that were linked to PLMS included depression, fibromyalgia, and diabetes.