Insomnia, also known as sleeplessness, is a sleep disorder that is characterized by difficulty falling asleep, staying asleep, or both. People with insomnia often feel dissatisfied with their sleep and may experience fatigue, low energy, difficulty concentrating, mood disturbances, and decreased performance at work or school.

Insomnia can be classified into two categories: acute insomnia and chronic insomnia. Acute insomnia is a short-term sleep disturbance that usually lasts for a few days or weeks, and it is often triggered by stress, travel, or changes in sleep environment or schedule. Chronic insomnia, on the other hand, is a long-term sleep disorder that lasts for months or years, and it is often associated with underlying medical or psychological conditions.

Insomnia can be treated with various approaches, including lifestyle changes, cognitive behavioral therapy, medication, and alternative therapies such as relaxation techniques and acupuncture. It is important to seek medical attention if insomnia persists and affects one's daily functioning and quality of life.