Title: 0716 OPTIMIZING ULTRADIAN FORCED DESYNCHRONY PROTOCOLS TO ASSESS INTRINSIC CIRCADIAN PERIOD
Abstract:Previous theoretical work has been used to optimize the extended day forced desynchrony (FD) protocol for reliable estimation of intrinsic circadian period in humans. Recently investigators have intro...Previous theoretical work has been used to optimize the extended day forced desynchrony (FD) protocol for reliable estimation of intrinsic circadian period in humans. Recently investigators have introduced ultradian FD protocols that require less time in the lab and are cost effective compared to longer FD protocols. However, a standard ultradian protocol has not yet emerged, and the effects of protocol design on estimated intrinsic periods have not been formally quantified. To address this gap, we applied a mathematical model of the human circadian pacemaker to investigate the parameters of the ultradian protocols and their effect on estimated intrinsic period. We simulated ultradian FD protocols with varying periods, light levels, and study lengths. Since the intrinsic period of the model pacemaker was known, deviations between observed and actual periods under different protocol conditions could be quantified precisely. We found that estimates of intrinsic period under ultradian FD protocols depended on the light level during wake episodes, the scheduled period, and the length of the study. Higher light levels corresponded to larger deviations between observed and actual periods. The rate of convergence of the observed period to the intrinsic period varied for different protocols, suggesting that the optimal study length depended on the scheduled period of the protocol. Using a mathematical model of the human circadian pacemaker, we quantified the dependence of observed circadian period on different features of ultradian FD protocols. This analysis establishes a theoretical framework that may be used to optimize the design of ultradian FD protocols to address specific research questions requiring accurate assessment of intrinsic circadian periods. NSF DMS 1412571 (CDB).Read More
Title: $0716 OPTIMIZING ULTRADIAN FORCED DESYNCHRONY PROTOCOLS TO ASSESS INTRINSIC CIRCADIAN PERIOD
Abstract: Previous theoretical work has been used to optimize the extended day forced desynchrony (FD) protocol for reliable estimation of intrinsic circadian period in humans. Recently investigators have introduced ultradian FD protocols that require less time in the lab and are cost effective compared to longer FD protocols. However, a standard ultradian protocol has not yet emerged, and the effects of protocol design on estimated intrinsic periods have not been formally quantified. To address this gap, we applied a mathematical model of the human circadian pacemaker to investigate the parameters of the ultradian protocols and their effect on estimated intrinsic period. We simulated ultradian FD protocols with varying periods, light levels, and study lengths. Since the intrinsic period of the model pacemaker was known, deviations between observed and actual periods under different protocol conditions could be quantified precisely. We found that estimates of intrinsic period under ultradian FD protocols depended on the light level during wake episodes, the scheduled period, and the length of the study. Higher light levels corresponded to larger deviations between observed and actual periods. The rate of convergence of the observed period to the intrinsic period varied for different protocols, suggesting that the optimal study length depended on the scheduled period of the protocol. Using a mathematical model of the human circadian pacemaker, we quantified the dependence of observed circadian period on different features of ultradian FD protocols. This analysis establishes a theoretical framework that may be used to optimize the design of ultradian FD protocols to address specific research questions requiring accurate assessment of intrinsic circadian periods. NSF DMS 1412571 (CDB).