しゅうきせいししうんどうしょうがい
周期性四肢運動障害
Periodic limb movement disorder (PLMD)
睡眠時、一定の時間に足の筋肉への痙攣（けいれん）運動が起こること。睡眠が浅くなり途中で目が覚めやすくなるために不眠の原因となる。高齢者、透析患者に多い。
This is when the leg or arm muscles spasm for a period of time during sleep. It makes sleep shallow and can easily wake a person up, and is therefore one of the causes of insomnia. It is common in the elderly and people undergoing dialysis.