People with ADHD are at a heightened risk of developing sleep disorders and often experience troubles falling or staying asleep. Because of this, many people feel drowsiness during the day and may even start to feel stressed about sleeping. This stress can actually make insomnia worse, causing an even more agitated sleep-wake schedule. A circadian rhythm is a 24-hour cycle that the human body follows through physical, mental, and behavioral changes. People with ADHD experience sleep issues because of a delay in their circadian rhythm, which results in delayed melatonin production. Unfortunately, lack of sleep can cause many uncomfortable symptoms such as irritability, restlessness, distractibility, etc., which are all symptoms of ADHD (Pacheco).