The results may indicate a "ceiling" was reached in the phase delay
of the human circadian clock due to the external factors, Wright said.
The "morning" time at which Ancoli-lsreal's subjects were given bright light therapy may have in actuality been their biological "evening" thereby resulting in a phase delay
rather phase advance.
Several complications may appear using the phase delay
from the monopole model.
Those shifts include phase delays
in which the peak of a body rhythm (such as a peak in temperature) occurs at, or shifts, to a point later in the cycle.
Puberty (the teen growth stage when reproductive organs become mature) causes a circadian phase delay
, or a shift of as much as two hours in the daily schedule of sleep and wakefulness, according to sleep expert Mary Carskadon of Brown University in Providence, Rhode Island.
The second illustrates sleep phase delay
syndrome, a disorder of sleep timing rather than of sleep itself.
Workers preferred the new schedule with phase delay
Machine induced errors include amplitude roll-off with frequency, amplitude scaling and phase delay
errors in the transducer conditioners and data acquisition devices and servo-loop non-linearities.
Additionally, the low phase delay
(2os) enables fast closed loop control and improves responsiveness in high-dynamic applications such as industrial servo motors, robotics and electric power steering.
Evening bright light treatment in the Ancoli-lsreal study, caused the expected delay in subjects' sleep/wake phases but it was surprising that morning bright light treatment also caused a phase delay
in sleep/wake periods rather than the expected phase advance.
It is not included in the works of each phase delay
Beginning at the onset of puberty, adolescents develop as much as a two-hour sleep-wake phase delay
(later sleep onset and wake times) relative to sleep-wake cycles in middle childhood," the authors write in the July issue of Archives of Pediatrics and Adolescent Medicine, one of the JAMA/Archives journals.