Isolated phasic discharges in anterior tibial muscle: a stable feature of paradoxical sleep.

Phasic muscle discharges known currently as "fasciculations" are more frequently encountered in the limb skeletal muscles and predominate in the lower limbs when compared with the upper limbs. Of the lower limbs, the most active during paradoxical sleep (PS) is the anterior tibial muscle. When quantifying phasic discharges of the eyes versus a lower limb muscle during PS, the former are 14 times more frequent than the latter. During PS there is a sporadic and nonsignificant decrease in the tonus of the antigravitational extensor muscles. Isolated phasic discharges in anterior tibial muscles are a stable feature of PS.