insomnia isn't due to medical problems, medicines, or other substances. It is its own distinct disorder, and its cause isn’t well understood. Many life changes can trigger primary insomnia, including long-lasting stress and emotional upset.
Insomnia can cause daytime sleepiness and a lack of energy. It also can make you feel anxious, depressed, or irritable. You may have trouble focusing on tasks, paying attention, learning, and remembering. These problems can prevent you from doing your best at work or school.
Insomnia also can cause other serious problems. For example, you may feel drowsy while driving, which could lead to an accident.