. >> reporter: for people with ffi, that quiet time never comes. the part of the brain regulates sleep. the thalmus functions like a traffic light. because of the destruction of the thalmus the person can't go to sleep. >> this woman is preparing for her wedding day but her father won't be walking her down the aisle. he and eight other relatives died of ffi. >> there was memory issues and muscular issues and it progressed and progressed. >> reporter: meagan fears she could be next. she has a 50% chance of inheriting ffi but has chosen not to ache a blood test to learn her fate. >> i would put a time line on my life and i'm not sure i could live like that. finding out i don't have it would make my life incredible but if i found out i did, it might ruin it. >> reporter: ffi is sleeplessness in its most rare form. >> an individual who has sleep deprived himself for one single night is as impaired as somebody who is legally intoxicated. >> reporter: dr. bornemann is one of the top sleep experts in the country. i think in general, americans are getting