Free-running sleep

Sleep that is not artificially regulated. Free running sleep is a form of chronotherapy? that can be used in curing selected [sleep disorders]?. Most of people in industrial world are not able or cannot afford free-running sleep. Only a small proportion of population can sleep in a perfect 24 hours cycle and in synchrony with duties such as job and family. The most typical violation of the free-running sleep is the use of an alarm clock. The other violation is going to sleep too late in reference to one's natural bed-time hour. Going to sleep very late in circumstances of reduced sleepiness does not violate free-running sleep. Going to sleep too early (e.g. to force longer sleep before early arising) may also disturb free-running sleep cycle.