A sleep disorder characterized by difficulty in falling asleep or remaining asleep throughout the night is ________.

A) zombulism
B) cataplexy
C) narcolepsy
D) insomnia

Insomnia

Difficulty in falling asleep or staying asleep, even when a person has the chance to do so, affecting physical and mental health.

Falling Asleep

The transition from wakefulness to sleep, marked by a decrease in bodily movement, responsiveness to external stimuli, and eventual entry into the sleep cycle.

Remaining Asleep

The state or condition of continuing to be asleep after initially falling asleep, often considered in the context of sleep quality and disorders.