Alexithymia is a personality trait characterized by the inability to identify and describe emotions experienced by one's self and others.

It was first described, and named, in 1970, but a precise definition of the trait is still lacking :

There is ongoing uncertainty about the structure and definition of alexithymia. Conceptually, alexithymia has traditionally been defined as a multidimensional trait with four components: difficulty identifying feelings, difficulty describing feelings, externally orientated thinking, and difficulty fantasizing. However, some authors suggest that difficulty fantasizing might not be a component, and others suggest low emotional reactivity is a fifth component.

Source : Personality Journal, Volume 88, Issue 6

Some research groups estimate that it may affect as many as 10% of the population.

The causes of Alexithymia are unknown. There is speculation that it may arise due to a deficit in electro-chemical communication between the right and left hemispheres of the brain.

Further technical details : Psychother Psychosom 2021;90:145–155