Most people experience sleep problems at some point in their life. This is normal. But when a person has a persistent problem with the quality, timing, or amount of sleep they get, and when their sleep problem causes distress and difficulties with functioning during the daytime, they may have a sleep disorder.
Although it's not always the case, sleep disorders often co-occur with other physical and mental health issues. A sleep disorder can cause or contribute to other medical and mental health conditions, or conversely, it can be a symptom of other conditions.