Which of these is the best sign that someone might be

dealing with a mental health disorder?

You could tell the person is dealing with a mental health disorder if you see changes in their sleeping or eating habits, is anger all the time, changes in their behavior, and not being able to handle their responsibilities. As in, not having the motivation to get out of bed or that chair and get things done. You could also tell through mood swings, and abuse of substance. The scariest one is anosognosia. That is when a sign of a mental disorder is the actual inability to see changes in behavior, feelings or personality. This is one reason many people don't know they are dealing with an actual illness. They may not even be aware of any changes. It may take a friend or a loved one to make them realize something is wrong