Free-running sleep is
sleep that is not artificially regulated. It is used as a form of
chronotherapy[?] that can help to cure some
sleep disorders. Most people in the industrial world cannot afford free-running sleep. Only a small part of the population can sleep in a perfect 24 hour cycle and in synchrony with the schedules demanded by work and family. The most typical violation of free-running sleep is the use of an
alarm clock[?]. Another violation is staying awake past one's accustomed bedtime in spite of drowsiness. (Staying up late when one is not sleepy does not violate free-running sleep.) Going to sleep too early (e.g. to force longer sleep before early arising) may also disturb the free-running
sleep cycle[?].