While much of morning and evening preference is heritable, the allele causing FASPS was hypothesized to have a quantitatively larger effect on clock function than the more common genetic variations that influence these preferences. Additionally, the circadian phase of subjects was determined using plasma melatonin and body core temperature measurements; these rhythms were both phase-advanced by 3–4 hours in FASPS subjects compared with control subjects. The Ptáček group also constructed a pedigree of the three FASPS kindreds which indicated a clear autosomal dominant transmission of the sleep phase advance.In 2001, the research group of Phyllis C. Zee phenotypically characterized an additional family affected with ASPS. This study involved an analysis of sleep/wake patterns, diurnal preferences (using a Horne-Östberg questionnaire), and the construction of a pedigree for the affected family. Consistent with established ASPS criteria, the evaluation of subject sleep architecture indicated that the advanced sleep phase was due to an alteration of circadian timing rather than an exogenous (i.e. externally-derived) disruption of sleep homeostasis, a mechanism of sleep regulation. Furthermore, the identified family was one in which an ASPS-affected member was present in every generation; consistent with earlier work done by the Ptáček group, this pattern suggests that the phenotype segregates as a single gene with an autosomal dominant mode of inheritance.In 2001, the research groups of Ptáček and Ying-Hui Fu published a genetic analysis of subjects experiencing the advanced sleep phase, implicating a mutation in the CK1-binding region of PER2 in producing the FASPS behavioral phenotype.
Gephyrophobia is the anxiety disorder or specific phobia characterized by the fear of bridges and tunnels. As a result, sufferers of gephyrophobia  may avoid routes that will take them over bridges, or if they are a passenger, will act very apprehensively when passing over a bridge. The term gephyrophobia comes from the Greek γέφυρα (gephura), meaning "bridge", and  φόβος (phobos), meaning "fear".Some possible manifestations of gephyrophobia may be fear of driving off the bridge, fear of a gust of wind blowing one off the bridge, or fear that the bridge will collapse when crossing it (e.g., fear that the bridge lacks structural integrity). The fear overlaps with acrophobia (the fear of heights) as gephyrophobia tends to be exacerbated in taller bridges as compared to those closer to the water or ground beneath. Dr. Michael Liebowitz, founder of the Anxiety Disorders Clinic at the New York State Psychiatric Institute, says, "Its not an isolated phobia, but usually part of a larger constellation ... Its people who get panic attacks. You get light-headed, dizzy; your heart races. You become afraid that youll feel trapped." It is a situational phobia.As of 2008, the New York State Thruway Authority would lead gephyrophobiacs over the Tappan Zee Bridge. A driver could call the authority in advance and arrange for someone to drive their car over the bridge for them.