The stages that comprise sleep, as well as sleep latency onset, are collectively called (1 point)

 The stages that comprise sleep, as well as sleep latency onset, are collectively called slow-wave sleep (SWS).
They occur during the first third of the night. Stage 3 lasts only a few minutes and constitutes about 3 to 8 percent of sleep, while stage 4  lasts approximately 20 to 40 minutes in the first cycle and makes up about 10 to 15 percent of sleep.