Periodic leg movements in sleep (PLMS) are repetitive jerks of one or both legs at night while asleep. The bedpartner notices the leg jerks much more frequently than the patient. The leg jerks can wake up the patient, but usually the awakening is so brief that the person never notices it. These awakenings, however, can lead to daytime sleepiness. PLMS get more common with age. Sometimes they are associated with restless legs syndrome which is the uncomfortable urge to move the legs at night before falling asleep.
Studies have begun to suggest that PLMS can increase the risk of cardiovascular disease and neurocognitive deficits (like memory or concentration problems). Researchers think this occurs because the leg movements cause activation of the sympathetic nervous system - in some cases hundreds of times per night. This nervous system activation can temporarily increase blood pressure and heart rate - over time, this could damage the heart and blood vessels.
There is a study in the journal Circulation where researchers performed in-home sleep studies on 2911 men greater than 65 years old to assess for PLMS and followed them for upto 4 years to assess how many went on to develop cardiovascular disease. Results showed that 70% of the men had PLMS. Patients that had even a mild amount of PLMS had greater rates of cardiovascular disease. Those with more frequent PLMS had 25-30% greater risk of developing cardiovascular disease than those without PLMS.
I wonder if the men with PLMS had subtle obstructive sleep apnea (OSA), as repetitive leg movements in sleep can be due to collapse of the airway. OSA is known to increase the risk of cardiovascular disease. Even if the patients in this study had true PLMS not from OSA, it is not clear if treating the PLMS will reduce the risk of developing cardiovascular disease - more studies are needed for that. In the meantime, it is important to talk to your doctor if your bedpartner notes that you jerk your legs at night while asleep.