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.
Advanced Sleep Phase Disorder (ASPD), also known as the advanced sleep-phase type (ASPT) of circadian rhythm sleep disorder, is a condition that is characterized by a recurrent pattern of early evening (e.g. 7-9 PM) sleepiness and very early morning awakening (e.g. 2-4 AM). This sleep phase advancement can interfere with daily social and work schedules, and results in shortened sleep duration and excessive daytime sleepiness. The timing of sleep and melatonin levels are regulated by the bodys central circadian clock, which is located in the suprachiasmatic nucleus in the hypothalamus. Symptoms
Individuals with ASPD report being unable to stay awake until conventional bedtime, falling asleep early in the evening, and being unable to stay asleep until their desired waking time, experiencing early morning insomnia. When someone has advanced sleep phase disorder their melatonin levels and core body temperature cycle hours earlier than an average person. These symptoms must be present and stable for a substantial period of time to be correctly diagnosed. Diagnosis
Individuals expressing the above symptoms may be diagnosed with ASPD using a variety of methods and tests. Sleep specialists measure the patients sleep onset and offset, dim light melatonin onset, and evaluate Horne-Ostberg morningness-eveningness questionnaire results. Sleep specialists may also conduct a polysomnography test to rule out other sleep disorders like narcolepsy. Age and family history of the patient is also taken into consideration. Treatment
Once diagnosed, ASPD may be treated with bright light therapy in the evenings, or behaviorally with chronotherapy, in order to delay sleep onset and offset.