A scientific name to describe people who are extreme "morning larks"? Do we need to a medical term for this? Is this making a normal aspect of some human life into a disease, a case of disease mongering. Maybe. But sleep researchers and therapists use the term and it does describe a segment of the population and is useful for research into the mysteries of sleep.
Advanced Sleep-Phase Syndrome is when the circadian phase is shifted earlier, so the person rises early and goes to bed early. The exact length of time shift is somewhat undefined and up to the diagnosing physician, but ASPS patients sometimes wake up refreshed as early as 2 or 3 AM and feel the need to go to bed at 7 PM. It is rare. It is estimated that about 1% of middle-aged and elderly people have ASPS. Another survey of thousands of people in Norway found not one respondent had ASPS as defined by International Sleep Disorder Classification criteria.
Is this shift necessarily bad? Not unless it interferes with their lives. Social demands may make it uncomfortable for the person with ASPS, and if they are expected to drive a car when they are drowsy in the evening, that can be dangerous. Work and school schedules may be difficult to work with, but people with the condition generally manage to do so. ASPS is sometimes called "social jet lag".
Note that ASPS is not a case of circadian de-synchronization as may happen to people with free-running syndrome or who are confined to dark spaces for long periods of time. It is not a case that the body does not respond to daylight and other cues; it’s just a case that ASPS person’s body is ahead of the rest of the population. You could tell an evolutionary story about this anticipation of diurnal patterns conveying a competitive advantage, but the relatively low prevalence of the pattern and the fact that it also shows up later in life tends to cast skepticism on this idea.
If a person with ASPS complains to a doctor it will usually be about waking up too early in the morning or getting drowsy too early in the evening. "Too early" is a social construct, of course, and if left alone with no work or social demands, the ASPS person can function normally. Morning rise times, even if they are at 3 AM, happen after a normal amount of sleep and there is not any excessive daytime sleepiness unless there is another problem. ASPS is a dyssomnia, but only in a social context.
Melatonin levels, blood pressure, hormone levels and other circadian markers also shift in people with ASPS. Body temperature is at its lowest earlier in the morning than for people without the syndrome. This syndrome runs in families. You even see the phrase "Familial advanced sleep phase syndrome" in the scientific literature. Although some of this tendency is learned, no doubt, researchers have also identified an inherited component. If we use the 2-phase model of sleep (homeostasis and circadian), it is easy to see that a change in the interaction of the two cycles may gradually adjust sleep time over time. Indeed, most people move backward in sleep time as they get older. For some, the shift is dramatic enough to constitute ASPS.
If a doctor really wanted to do a formal diagnosis, he or she could order actigraphy, or perhaps an overnight sleep study to look at circadian timing details. ASPS can easily be mistaken for depression which also causes early morning awakenings.
Therapy is confined to behavioral changes and possibly phototherapy. Although it is possible to make a person sleepy or alert with drugs, and short-term shifting of the circadian cycle may be possible with melatonin, these are not long-term solutions. Light therapy - the exposure to artificial light to reset the circadian clock - is the best artificial method. Planned trips outdoors for exposure to daylight can also help. This is similar to the situation with jet lag sufferers who seek outdoor sunlight exposure to encourage their internal circadian clocks to match nature's.