A discussion of movement disorders affecting sleep brings us to PLMD (note the "L") and RLS. The L stands for legs, the limbs most affected in these disorders. In PLMD (periodic limb movements disorder), periodic leg movements disrupt the sufferer's night: Legs jerk repeatedly, kicking every 20 to 40 seconds through the night. Not surprisingly, these leg kicks trigger frequent arousals. The end result? Daytime sleepiness and nighttime insomnia.
While PLMD may be diagnosed infrequently by primary care physicians, the disorder is all too common among the elderly. In one study, approximately 45 percent of the elderly had at least a mild form of PLMD. As with sleep apnea, evaluation at a sleep disorders center is the first step.
Drug treatment can be very successful, with anti-Parkinsonian drugs (e.g., carbidopa-levodopa) controlling the majority of cases. Other medications include dopamine agonists and sedative-hypnotics (calming, sleep-inducing medications). Patients should be monitored closely during treatment for side effects or adverse reactions. Achieving the proper dose of the most effective medication may take time.
Are You a Nightwalker?
RLS, or restless legs syndrome, is less common than PLMD. The distinction between the two disorders is that in RLS, the leg movements occur continually when the body is at rest. The movements of PLMD occur in sleep.
RLS symptoms include an uncomfortable sensation in the foot, calf or upper leg that feels like something is crawling or moving inside the limbs, or tickling or aching deep inside them. This sensation is yoked with a compulsion to move the legs. Movement resolves the symptoms, but the syndrome is unrelenting. Within seconds or minutes, the sensations return. If the legs are not moved, they frequently jump involuntarily. Since rest brings on symptoms, and walking offers relief, sufferers are often called nightwalkers.
Symptoms are always worse at night and sometimes only present nocturnally. If individuals do manage to fall asleep, leg movements lead to frequent awakenings or near awakenings. Next-day fatigue is endemic.
Although the precise cause of RLS remains a mystery, in some cases, RLS may be due to iron deficiency, dialysis, pregnancy or peripheral neuropathy. Iron deficiency is a common and eminently treatable cause. Pregnancy, of course, is time-limited. In some cases, polysomnographic evaluation may not be indicated. However, there are other cases, particularly if there is accompanying neurologic disease, or if the movements have an aggressive or generalized quality to them, that may require a polysomnographic evaluation. Treatment can begin immediately with the same range of medications as indicated for PLMD.
Do You Act Out Your Dreams?
One sleep disorder combines dreams with movement: REM sleep behavior disorder. Most sleepers are virtually paralyzed during REM or dreaming sleep; people with REM sleep behavior disorder do not have this motor inhibition and literally act out their dreams. They may crash into furniture, break windows or fall down stairs, leading to self-injury or hurting others. Such sleep is hardly restful! Most sufferers are men over 50. Drug treatment with clonazepam can eliminate the dream disturbances and improve sleep for sufferers and those who live with them.
