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Periodic limb movement disorder (PLMD) is an idiopathic condition, which means that its cause is unknown. It may occur in conjunction with other conditions, but it may also occur on its own.

Certain conditions have been associated with PLMD. Patients with these conditions may have an increased risk of developing PLMD. These conditions include:

• Restless leg syndrome
  
  
• Parkinson’s disease
  
  
• Attention deficit hyperactivity disorder (ADHD)
  
  
• Other sleep disorders (e.g., narcolepsy, obstructive sleep apnea, REM sleep behavior disorder)
  
  
• Kidney disease
  
  
• Spinal cord injury

There are several additional risk factors that may increase a patient’s risk of developing PLMD, including:

• Age. The occurrence of PLMD increases after the age of 40, with a large number of cases occurring among those 65 and older.
  
  
• Family history. There is some evidence that similar disorders (e.g., restless leg syndrome) may be related to inherited genetic mutations. Therefore, PLMD may be more likely to occur in patients who have family members with the disorder.
  
  
• Poor sleep hygiene. Certain behaviors and conditions are likely to reduce a patient’s overall ability to sleep and may increase the risk of developing PLMD. These include consuming alcohol, tobacco or caffeine close to bedtime. Engaging in strenuous exercise and intense mental activity in the late evening may also lead to PLMD.

In addition, certain medications are believed to induce or increase the likelihood of PLMD. Treatments with antidopaminergic, dopaminergic, or tricyclic antidepressants or cessation of barbiturates or benzodiazepines that change the concentration of the neurotransmitter dopamine  may initiate PLMD as well. Other medications may also worsen a patient’s PLMD, including lithium (often used to treat bipolar disorder) and some anti-nausea drugs.