While anxiety is not the central focus of the novel, several characters explicitly mention having the condition, and the character of Lydia refers to anxiety as the most common mental health condition in the United States, a fact supported by medical statistics. It is estimated that anxiety impacts nearly one in five adults, and over 200 million people worldwide deal with an anxiety disorder of some kind. Women are also twice as likely to be diagnosed as men (“Anxiety Disorders.” WHO).

Anxiety is a normal response to stress, and as suggested in the book, is considered to be a coping strategy that intensifies people’s awareness of their surroundings. However, anxiety becomes a disorder when its expression interferes with normal, day-to-day functioning. These types of severe, sustained, and extensive fears or worries may be classified as disorders such as generalized anxiety disorder (GAD), panic disorder, social anxiety disorder, or specific phobias. Those who have anxiety report feeling nervous, irritable, and apprehensive, and the condition can also cause increased heart rate, hyperventilation, fatigue, insomnia, and gastrointestinal problems.

Those who experience generalized anxiety disorder often feel excessive anxiety and worry about ordinary activities, and panic disorder involves sudden attacks of terror despite the lack of any physical threat.