The body is at its lowest level of functioning during _____ sleep.

In studies in which volunteers spend several days without access to information about day or night, their sleep–wake cycles

Predators such as lions sleep _____ their prey, the gazelle.

In the early stages of sleep, _____ waves appear.

Many researchers believe that reports of ghostly visions and alien abductions can be explained by _____ during N1 sleep.

Which of the following statements about REM sleep is true?

Nearly _____ percent of a baby's sleep is REM, compared to about _____ percent for a normal, healthy adult.

Mateo is often a victim of bad dreams, frequently centered around being left at a store or getting lost at an amusement park. He sometimes wakes up from them, and calls for his parents to help him calm down. Mateo is experiencing

Night terrors are experienced