Matthew Ratcliffe created a new category of feelings that can not be covered with the terms: ‘mood’ or ‘emotion’. These feelings are existential feelings. Existential feelings are feelings that in some way describe how we relate toward the world or our own body. They draw inspiration on Heideggers concept of Mood. But in contrast to Heidegger’s concept of Mood they can endure for seconds up till an entire lifetime. The concept of existential feelings also solves many linguistic confusion that the everyday use of the term mood creates. Existential feelings play a role in many different psychiatric disorders. Especially in those disorders that change the sense of reality or the sense of selfperception. Ratcliffe illustrates this by showing the role of existential feelings in self perception in the Cotard Delusion and the role of existential feelings in perception of reality in the capgrass delusion. The critique that existential feelings only play a role in rare psychiatric disorders is unjust. This is illustrated in this thesis by a reflection upon the role of existential feelings in a very common psychiatric disorder, namely depersonalization disorder. Knowledge of existential feelings and their role in psychiatric disorders can improve our knowledge of the experience of psychiatric disorders. It also allows us to further understand potential pathological processes in psychiatric disorders. It also improves our possibility to show empathy for patients with psychiatric disorders, since it allows us to create the language that is needed to communicate about what people are experiencing. The existence of pathological existential feelings and their role in psychiatric disorders is not yet clear. However it is not necessary for this to be clear in order for existential feelings to be a useful concept that is able to improve our empathy for psychiatric patients.