Which of the following is a primary symptom of insomnia?

The primary symptom of insomnia is characterized by difficulty falling asleep or staying asleep. This condition can manifest in various forms, including trouble initiating sleep, frequent awakenings during the night, and waking up too early without the ability to return to sleep. The core aspect of insomnia is the impact it has on nighttime sleep quality and duration, which subsequently disrupts daytime functioning.

While excessive sleepiness during the day is often a consequence of poor sleep, it stems from the underlying issue of insomnia itself rather than being a direct symptom. Frequent nightmares and a consistent need for napping are related to different sleep disorders or sleep-related issues that do not specifically define insomnia. In essence, the definitive feature of insomnia revolves around the difficulties encountered with sleep onset and maintenance.