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Sleep-Related Movement Disorders

Sleep-related movement disorders involve physical movements which may be irresistible or involuntary, occur during sleep or periods of rest, and frequently result in insomnia and daytime fatigue.

Restless Legs Syndrome
Restless legs syndrome (RLS) is a common disorder characterized by unpleasant sensations deep inside the legs. These sensations primarily occur when the patient is sedentary during rest periods and can become more pronounced during bedtime. The paresthesias are accompanied by an irresistible urge to move the limb, which results in a temporary relief of symptoms. Approximately 80% of patients with RLS have periodic limb movements of sleep (PLMS). RLS can result in sleep-onset insomnia as well as difficulties in returning to sleep following nocturnal awakenings. Patients often complain of excessive daytime sleepiness and fatigue.

Learn more about Restless Legs Syndrome.

Periodic Limb Movement Disorder
PLMD is a condition in which frequent and involuntary muscle spasms occur only during sleep. These are stereotyped, periodic, jerking movements typically consisting of flexion of the ankle, knee, and hip. PLMS are regularly accompanied by an awakening resulting in sleep fragmentation and subsequent excessive daytime sleepiness, although this is controversial. In virtually all patients with RLS, PLMS are observed, however patients with PLMD do not necessarily experience RLS. There is some evidence that certain antidepressants, such as venlafaxine or selective serotonin reuptake inhibitor groups, may lead to the development of PLMS.

Sleep Starts
Sleep starts, also referred to as hypnic jerks, are spontaneous muscle twitches of various body parts that occur throughout the night, typically during sleep onset. Sleep starts arising in the relaxation and drowsiness period preceding sleep onset have been reported to cause severe sleep-onset insomnia. One may experience a feeling of falling or other sensory hallucination during the occurrence.

Sleep-Related Leg Cramps
Sleep-related leg cramps are painful muscle contractions which occur during sleep. Leg cramps are common occurrences among the elderly. The spasms are involuntary and begin abruptly at irregular times throughout the night. The painful experiences may delay sleep onset or trigger arousals from sleep. Relief is achieved through stretching of the muscle, massage, or heat.

Bruxism is characterized by grinding or clenching of the teeth. Grinding is defined as sliding teeth back and forth over each other. Clenching is defined by tightly holding the top and bottom teeth together.