Video analysis of gross body movements during sleep

Gross body movements (GM) during sleep, classified into four GM types by the involved parts of body, were evaluated using two‐dimensional video analysis in five normal children aged 4–12 years. The rate of occurrence of all GM types showed apparent sleep stage dependency. Among four GM types, GM‐1 (GM with axial rotation) was the most frequent. Averaged duration of GM‐1 was the longest. A total of 77.2% of GM‐1 started with the contraction of chin muscle and 35% of total sleep changes (tSC) were related to GM. A total of 5.6% of tSC following GM shifted to the deeper stage. Further evaluation is necessary in order to understand the physiological mechanism of GM.