Restless legs syndrome and its correlation with other sleep problems in the general adult population of Japan

The epidemiological study presented here was conducted to examine the association between sleep problems and restless legs syndrome (RLS) among a large sample taken from the general population of Japan. The presence of RLS was established by asking the subjects if they experienced a crawling sensation in their legs after going to bed. This survey was performed in June 2000, targeting a sample that was randomly selected from 300 communities throughout Japan. The questionnaire contained questions focusing on health consciousness, mental health, and sleep. A total of 26705 participants completed the questionnaire. The prevalence of RLS was 3.0%, with a significant predominance in women. The prevalence of RLS increased significantly with advancing age. Multiple logistic regression analysis revealed that RLS was significantly associated with difficulty initiating sleep (odds ratio, OR = 2.58), excessive daytime sleepiness (OR = 2.28), difficulty maintaining sleep (OR = 1.71), non-restorative sleep (OR = 1.51), subjective insufficient sleep (OR = 1.36), and early morning awakening (OR = 1.21). These results suggest that the prevalence of RLS in Japan is lower than in northern European populations and that RLS is strongly associated with difficulty initiating sleep and excessive daytime sleepiness.