Advanced sleep phase type is characterized by sleep-wake times that are several hours earlier than desired or conventional times. Diagnosis is based primarily on a history of an advance in the timing of the major sleep period (usually more than 2 hours) in relation to the desired sleep and wake—up time, with symptoms of early morning insomnia and ex- cessive daytime sleepiness. When allowed to set their schedule, individuals with ad- vanced sleep phase type will exhibit normal sleep quality and duration for age.
Individuals with advanced sleep phase type are ”morning types,” having earlier sleep— wake times, with the timing of circadian biomarkers such as melatonin and core body tem- perature rhythms occurring 2—4 hours earlier than normal. When required to keep a con- ventional schedule requiring a delay of bedtime, these individuals will continue to have an early rise time, leading to persistent sleep deprivation and daytime sleepiness. Use of hyp- notics or alcohol to combat sleep-maintenance insomnia and stimulants to reduce daytime sleepiness may lead to substance abuse in these individuals.
The estimated prevalence of advanced sleep phase type is approximately 1% in middle— age adults. Sleep-wake times and circadian phase advance in older individuals, probably accounting for increased prevalence in this population.
Onset is usually in late adulthood. In the familial form, onset can be earlier. The course is typ- ically persistent, lasting more than 3 months, but the severity may increase depending on work and social schedules. The advanced sleep phase type is more common in older adults.
Clinical expression may vary across the lifespan depending on social, school, and work obligations. Individuals who can alter their work schedules to accommodate the advanced circadian sleep and wake timing can experience remission of symptoms. Increasing age tends to advance the sleep phase, however, it is unclear whether the common age-associ- ated advanced sleep phase type is due solely to a change in circadian timing (as seen in the familial form) or also to age-related changes in the homeostatic regulation of sleep, result- ing in earlier awakening. Severity, remission, and relapse of symptoms suggest lack of ad- herence to behavioral and environmental treatments designed to control sleep and wake structure and light exposure.
Environmental. Decreased late afternoon/early evening exposure to light and / or expo- sure to early morning light due to early morning awakening can increase the risk of ad- vanced sleep phase type by advancing circadian rhythms. By going to bed early, these individuals are not exposed to light in the phase delay region of the curve, resulting in per- petuation of advanced phase. In familial advanced sleep phase type, a shortening of the endogenous circadian period can result in an advanced sleep phase, although circadian pe- riod does not appear to systematically decrease with age.
Genetic and physiological. Advanced sleep phase type has demonstrated an autoso- mal dominant mode of inheritance, including a PERZ gene mutation causing hypophos- phorylation of the PERZ protein and a missense mutation in CKI.
vances to light than do Caucasians, possibly increasing the risk for development of ad- vanced sleep phase type in this population.
A sleep diary and actigraphy may be used as diagnostic markers, as described earlier for delayed sleep phase type.
Functional Consequences of Advanced Sieep Phase Type
Excessive sleepiness associated with advanced sleep phase can have a negative effect on cognitive performance, social interaction, and safety. Use of wake-promoting agents to substance abuse.
Other sleep disorders. Behavioral factors such as irregular sleep schedules, voluntary early awakening, and exposure to light in the early morning should be considered, partic- ularly in older adults. Careful attention should be paid to rule out other sleep-wake dis- orders, such as insomnia disorder, and other mental disorders and medical conditions that can cause early morning awakening.
Depressive and bipolar disorders. Because early morning awakening, fatigue, and sleep- iness are prominent features of major depressive disorder, depressive and bipolar disor- ders must also be considered.