Definitions

1. noun

a state of being unable to sleep or a sleep disorder characterized by difficulty in falling or staying asleep

“Her doctor suspected she had insomnia due to her irregular sleep schedule.”

2. noun

a period of wakefulness, especially one that occurs at night or early morning

“She woke up in the middle of the night and experienced a bout of insomnia.”

3. noun

a state of wakefulness or inactivity, often with a sense of being alert or vigilant

“The insomnia that had plagued him for months made it difficult to focus at work.”