By the time children are 5 years old:

Question

Quizplus · Accepted Answer

By the time children are 5 years old, the typical 90-minute sleep cycles of alternating REM and NREM sleep are established. Option A is incorrect because infants spend about 50 percent of their sleep time in REM sleep, whereas it decreases as they mature. Option B is incorrect because children's sleep cycles become longer with age. Option D is not necessarily true for all children, as some may have had dreams or nightmares before age 5.

By the Time Children Are 5 Years Old