Abstract: A method for accurately assessing and rapidly modifying the phase and amplitude of the endogenous circadian pacemaker is disclosed. A circadian cycle modification capacity assessment method comprises (before and after a stimulus) eliminating activity-related confounding factors associated with the sleep-rest cycle which otherwise mask the state of the endogenous circadian pacemaker. Based on either individual or normative assessment data, the circadian phase and amplitude modification method involves the application of bright (about 9,500 lux) light and, advantageously, episodes of imposed darkness, at critically chosen phases to achieve rapid and stable changes in phase and amplitude. The timing of the episodes of bright light may be chosen either by reference to empirically-derived phase response data, or by using a mathematical model in which the endogenous circadian pacemaker is a van der Pol oscillator.

Abstract: A method for accurately assessing and rapidly modifying the phase and amplitude of the endogenous circadian pacemaker is disclosed. A circadian cycle modification capacity assessment method comprises (before and after a stimulus) eliminating activity-related confounding factors associated with the sleep-rest cycle which otherwise mask the state of the endogenous circadian pacemaker. Based on either individual or normative assessment data, the circadian phase and amplitude modification method involves the application of bright (about 9,500 lux) light and, advantageously, episodes of imposed darkness, at critically chosen phases to achieve rapid and stable changes in phase and amplitude. The timing of the episodes of bright light may be chosen either by reference to empirically-derived phase response data, or by using a mathematical model in which the endogenous circadian pacemaker is a second order differential equation of the van der Pol type, transformed into two complementary first order equations.

Abstract: A method for accurately assessing and rapidly modifying the phase and amplitude of the endogenous circadian pacemaker is disclosed. A circadian cycle modification capacity assessment method comprises (before and after a stimulus) eliminating activity-related confounding factors associated with the sleep-rest cycle which otherwise mask the state of the endogenous circadian pacemaker. Based on either individual or normative assessment data, the circadian phase and amplitude modification method involves the application of bright (about 9,500 lux) light and, advantageously, episodes of imposed darkness, at critically chosen phases to achieve rapid and stable changes in phase and amplitude. The timing of the episodes of bright light may be chosen either by reference to empirically-derived phase response data, or by using a mathematical model in which the endogenous circadian pacemaker is a van der Pol oscillator.