What is fatal familial insomnia?
Fatal familial insomnia is a rare sleep disorder that is caused by a mutation in the gene that codes for the serotonin transporter. The serotonin transporter is responsible for converting serotonin into its active form, which helps to regulate mood and sleep. People with fatal familial insomnia have low levels of serotonin in their brains, which can cause them to have problems falling asleep and staying asleep.