circadian rhythm in heart rate and parasympathetic nerve activity after an
eastward transmeridian flight.
Tateishi O; Fujishiro K
Department of Laboratory Medicine, Jikei
of Medicine, Jikei, Japan. PBC01177@nifty.ne.jp
Distortions of the circadian
rhythm structure of the heart rate and parasympathetic nerve activity after an
eastward transmeridian flight were studied. We
recorded the ambulatory electrocardiograms of 12 healthy young men for 11 days:
3 days in Tokyo before the flight and 8 days in San Francisco following
it. Heart rate variability was determined by power spectrum analysis, and high
frequency power (0.15-0.4 Hz) was used as the index of parasympathetic tone.
The structural characteristics of the circadian rhythm were analyzed by
dividing consecutive RR data into four parts: the preflight days, the second
and third days, the fourth and fifth days (Days 5-6)
and the sixth and seventh days. Eight of the 12 cases were analyzed completely.
The circadian period of the heart rate decreased after the flight. The peak
time of parasympathetic nerve activity shifted from the small hours to the
daytime, the maximum shift being during days 5-6 after the flight. We concluded
that a structural disturbance of the circadian rhythm of the heart rate and
parasympathetic nerve activity were observed.