What type of sleep disorder is characterized by difficulty falling asleep or staying asleep?

Insomnia is characterized by difficulty falling asleep or staying asleep, making it the most appropriate choice for this question. Individuals with insomnia often experience a range of symptoms, including trouble initiating sleep, frequent awakenings during the night, or waking up too early and being unable to go back to sleep. This condition can lead to significant daytime impairment, affecting mood, productivity, and overall quality of life.

In contrast, sleep apnea is primarily characterized by episodes of interrupted breathing during sleep, often leading to excessive daytime sleepiness but not primarily a difficulty in falling or staying asleep. Restless leg syndrome involves uncomfortable sensations in the legs that typically occur when a person is at rest, prompting an urge to move the legs, which can complicate the sleep onset but doesn’t directly refer to the act of sleeping itself. Parasomnia encompasses abnormal behaviors during sleep, such as sleepwalking or nightmares, which are not primarily related to the difficulty of initiating or maintaining sleep. Thus, insomnia specifically focuses on sleep initiation and maintenance challenges, making it the clear choice for this question.