Epidemiology

The prevalence of primary periodic limb movements of sleep (PLMS), from small population-based studies, is estimated to range from 4% to 11% in adults.[4][8][9][10][11][12][13][14] The prevalence of PLMS is reported to be 29% in the middle to older aged general population.[15] 

A community-based study of 592 individuals in the US demonstrated a PLMS prevalence (defined as PLMS-I >15; where PLMS-I is the number of periodic limb movements per hour of sleep) of 7.6%. Black people had a significantly lower prevalence than white people. Regardless of race, symptoms of insomnia were significantly more common in individuals with PLMS-I >15.[8] Other studies have demonstrated that PLMS is more common in women, shift workers, individuals taking hypnotics, and those with high daily caffeine intake.[16]

Longitudinal studies in older adults have found an increased prevalence of PLMS with increased age, but sleepiness was only found to increase with comorbid restless legs syndrome (RLS).[17] One study reported a PLMD prevalence >80% in older patients with sleep disturbances.[11][12][13][14]​​ The prevalence of PLMD is particularly high in individuals with RLS (up to 80%).[6][7]

While studies are limited, it has been suggested that PLMS may be more common in younger groups than previously suspected, and that PLMD may be more common in children with ADHD.[9][10]

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