Does chronotherapy alter circadian rhythms (rectal temperature and sleep onset) in patients with delayed sleep phase syndrome?
Chronotherapy normalizes the period of rectal temperature rhythm and the interval between sleep onset and temperature minimum in patients with delayed sleep phase syndrome, suggesting a weakened entrainment mechanism in this condition.
To clarify the circadian aspects of delayed sleep phase syndrome (DSPS) in 4 patients with DSPS, we recorded polysomnograms and rectal temperature before and after chronotherapy. The time interval (2.7 h) between sleep onset and rectal temperature minimum before chronotherapy was shorter than the time interval after chronotherapy (5.3 h). Before chronotherapy, the period of rectal temperature rhythm was 24.7 h. After chronotherapy, the period of rectal temperature rhythm was 24.0 h. These findings lead to the conclusion that in DSPS there is a weakened mechanism of entrainment similar to that in non-24-hour sleep-wake syndrome.
Ozaki et al. (Wed,) studied this question.