Two movement disorders that can make it harder to sleep include restless legs syndrome, or RLS, and periodic limb movement disorder, or PLMD. Both of these conditions cause people to move their limbs when they sleep, leading to poor sleep and daytime drowsiness. Often, both conditions occur in the same person.
Restless legs syndrome is a common condition in older adults and affects more than 15 percent of people 80 years and older. People with RLS experience uncomfortable feelings in their legs such as tingling, crawling, or pins and needles. This often makes it hard for them to fall asleep or stay asleep, and causes them to be sleepy during the day.
Although scientists do not fully understand what causes restless legs syndrome, it has been linked to a variety of conditions. Some of these conditions include iron deficiency, kidney failure and dialysis, pregnancy, and nerve abnormalities.
Periodic limb movement disorder, or PLMD, is a condition that causes people to jerk and kick their legs every 20 to 40 seconds during sleep. As with RLS, PLMD often disrupts sleep -- not only for the patient but the bed partner as well. One study found that roughly 40 percent of older adults have at least a mild form of PLMD.