0675 Effects of Circadian Acclimation of Performance, Sleep, 6-sulfatoxymelatonin on Heart Rate & Heart Rate Variability

Abstract Introduction Jet lag is associated with transmeridian travel across at least two time zones, associated with sleep disturbance as well as daytime dysfunction. The presence of jet lag has been hypothesized to be associated with adverse cardiovascular outcomes; however, objective data are not available. Jet lag can have many negative effects on physical and mental health, mental and physiological performance, and sleep. The objective of this study is to understand the impact of simulated jet lag on heart rate. Methods Following a baseline circadian rhythm assessment, participants were placed on a 16 hour wake – 8 hour sleep schedule in which the wake-sleep and light-dark schedule was delayed by 8 hours for 3 days (analogous to traveling 8 time zones west). Participants were randomized to one of 3 treatments administered each of the 3 days of the shifted schedule: (A) placebo control, (B) bright light, and (C) bright light + exercise + melatonin. Participants wore an Extended Wear Holter Monitor for the duration of the 6.5 day laboratory stay. Minimum, average and maximum heart rates as well as heart rate variability were evaluated for each phase in the laboratory. Results 15 of the 22 patients enrolled wore the Holter monitor and completed the study (86.6% men, mean age 28.4 ± 9.56)— 5 were in the placebo arm, 7 in bright light, 3 in the bright light + exercise + melatonin group. In the placebo group, the average heart rate in beats per minute (± SD) increased in the first ultrashort period when compared to baseline (70 (6) vs. 66 (8), p =0.022). In the bright light group, the average heart rate (± SD) decreased during the shifted schedule when compared to baseline (70 (14) vs. 74 (4), p =0.015). No other significant changes were noted. Conclusion The initial induction of jet lag seems to have detrimental effects on heart rate, however the body adjusts thereafter and bright light may be helpful to reduce the impact of jet lag on heart rate. Support (if any) Department of Defense, Philips, American Academy of Sleep Medicine Foundation, National Institutes of Health, The University of Arizona.