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Tuesday, September 2, 2014
Number of Movements During Sleep
What is the normal number of movements during a night`s sleep?
Movements during sleep can be secondary to many causes, including normal sleep physiology (such as sleep starts, some leg jerks, foot tremors, etc), sleep disorders (such as periodic limb movements in sleep, obstructive sleep apnea or parasomnias) and even the side effects of certain medications. The answer to this question really depends upon further history about the nature of the movements you mention. Without knowing more specifics, it's impossible to tell you the "normal number of movements" during sleep. I'll briefly review some of the sleep disorders associated with movements in sleep.
Sleep (or Night) starts are a very common and are generally considered normal. These are usually startling jerks involving the legs or all four extremities at the onset of sleep. Night starts may occasionally awaken the affected individual immediately after he or she drifts to sleep. In the majority of cases, they do not need any treatment.
Nocturnal or night-time leg cramps are characterized by pain or unpleasant sensations associated with involuntary movements. This condition can be the result of a variety of reasons including dehydration, alcohol, electrolyte deficiency, certain medications, and exercise. Certain medical illnesses can give rise to leg cramps and these include diabetes, heart disease, or neuropathy (nerve disease). There is no acceptable minimal number of leg cramps. Any amount of leg cramps that is persistent or concerning to the patient is considered worthy of attention and treatment. The treatment will focus generally on avoiding the triggering factors, hydration, certain leg exercises, sleep hygiene, avoidance of caffeine and alcohol, and occasionally a short course of medication therapy.
A condition called periodic limb movement disorder of sleep (PLMD) can be more problematic. In this disorder, the patient experiences involuntary movements of the legs during sleep that follow a specific and repetitive pattern. These movements can result in brief awakenings and sleep disturbance. This condition can co-exist with its more famous awake time counterpart: Restless Leg Syndrome (RLS). These two conditions can be treated similarly. Overall, having some leg movements periodically during sleep does not constitute a disorder. In fact, most sleep physicians do not treat these movements if they were found incidentally on sleep studies that were done for other reasons, especially, if they were not associated with relevant complaints from the patient. Most sleep physicians do not consider periodic limb movements of sleep significant unless they exceeded an average number of 15 movements per hour of sleep. There are several causes of this disorder (PLMD); including medical illness or neuropathy. In some cases, iron deficiency is the cause and easily treated. In other cases, no cause can be identified, and treatment with medication is indicated.
Sometimes, leg movements in sleep may be the result of an arousal phenomena (awakening) that is due to another problem in sleep, such as obstructive sleep apnea. The arousal associated with the airway reopening can be quite frequent and appear periodic during sleep. Other movements in sleep can be due to less common conditions that can occur in sleep, such as parasomnias (abnormal behaviors in sleep) and seizures.
Again, to specifically answer your question, more information, and perhaps a complete history and physical examination may be needed. If you are concerned, I recommend you speak to your doctor, who can then determine if further evaluation or referral to a Sleep Specialist is needed.
Rami N Khayat, MD
Clinical Associate Professor of Pulmonary, Allergy, Critical Care & Sleep
College of Medicine
The Ohio State University