A recent study confirms that 6% of the adult US population experience nocturnal leg cramps (NLC) more than fifteen times in a month. Also, a significant relationship has been found between NLC and sleep disturbance symptoms and health conditions which suggest that NLC contributes to impoverished sleep and general health.

Nocturnal leg cramps are very common, but their pathophysiology is not appropriately recognized.

 A cross-sectional epidemiological study was designed to find out the prevalence of NLC and its associations with cardiometabolic, sleep, and behavioral risk factors in the US population. Participants from National Health and Nutrition Examination Survey, 2005-2006 and 2007-2008 waves were included.

The study outcome measures include the assessment of NLC via question - "In the past month, how often did you have leg cramps while trying to sleep?". The responses were categorized as None, Mild, or Moderate-Severe. Dataset of 2005-2006 was used to evaluate the risk factors like demographics, medical history, sleep disturbances, and cardiometabolic. Dataset of 2007-2008 was used to determine the variables that showed significant association with NLC after adjusting for age, sex, education, and BMI. A forward stepwise regression model combining both waves was used to evaluate which variables fully described the variation in NLC.

The incidence of NLC was reported as mild by 24-25% participants and as moderate-severe by 6%. NLC was found to be increased with age, lower education, unemployment, shorter sleep duration, all assessed sleep symptoms (nocturnal "leg jerks", snoring, snorting/gasping, difficulty falling asleep, difficulty maintaining sleep, non-restorative sleep, sleepiness, use of sleep medications), higher BMI, smoking, medical history (hypertension, heart failure, angina, stroke, arthritis, respiratory disease, and cancer), depression symptoms, and biomarkers (CRP, HbA1c, calcium, cadmium, red blood cells). Moderate-severe nocturnal leg cramps were found to be linked with (in decreasing order of partial R2): leg jerks, poor overall health, arthritis, difficulty falling asleep, age, nonrestorative sleep, red blood cell count, lower education, angina, and difficulty maintaining sleep as revealed by stepwise analysis.