Periodic limb movements in sleep are repetitive movements, most typically in the lower limbs, that occur about every 20-40 seconds. If you have PLMS, or sleep with someone who has PLMS (also referred to as PLMD, periodic limb movement disorder), you may recognize these movements as brief muscle twitches, jerking movements or an upward flexing of the feet. They cluster into episodes lasting anywhere from a few minutes to several hours.
The exact cause of PLMS is still unknown. Scientists believe that the underlying mechanisms probably involve factors in the nervous system, although studies have not revealed any consistent abnormalites. PLMS are not considered medically serious. They can, however, be implicated as a contributing factor in chronic insomnia and/or daytime fatigue because they may cause awakenings during the night. Occasionally, PLMS may be an indicator of a serious medical condition such as kidney disease, diabetes or anemia.
Individuals with PLMS may also experience restless legs syndrome (RLS), an irritation or uncomfortable sensation in the calves or thighs, as they attempt to fall asleep or when they awaken during the night. Walking or stretching may relieve the sensations, at least temporarily. However, research also shows that many individuals have PLMS without experiencing any symptoms at all. It's not unusual for the bed partner to be the one who's most aware of the movements, since they may disturb his/her sleep.
Seek professional medical advice. You may wish to begin by consulting your family physician or find a sleep professional.