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Clin Neurophysiol. 2001 Jun;112(6):992-6.

Inverse coupling between ultradian oscillations in delta wave activity and heart rate variability during sleep.

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Laboratoire des RĂ©gulations Physiologiques et des Rythmes Biologiques chez l'Homme, 4 rue Kirschleger, 67085 Cedex, Strasbourg, France.



We investigate the relationship between changes in heart rate variability and electroencephalographic (EEG) activity during sleep.


Nine male subjects with regular non-rapid-eye movement-rapid-eye movement (NREM-REM) sleep cycles were included in the study. They underwent EEG and cardiac recordings during one experimental night. Heart rate variability was determined over 5-min periods by the ratio of low frequency to low frequency plus high frequency power [LF/(LF+HF)] calculated using spectral analysis of R-R intervals. EEG spectra were analyzed using a fast Fourier transform algorithm.


We found an ultradian 80-120 min rhythm in the LF/(LF+HF) ratio, with high levels during rapid eye movement (REM) sleep and low levels during slow wave sleep (SWS). During sleep stage 2 there was a progressive decrease in the transition from REM sleep to SWS, and an abrupt increase from SWS to REM sleep. These oscillations were significantly coupled in a 'mirror-image' to the overnight oscillations in delta wave activity, which reflect sleep deepening and lightening. Cardiac changes preceded EEG changes by about 5 min.


These findings demonstrate the existence of an inverse coupling between oscillations in delta wave activity and heart rate variability. They indicate a non-uniformity in sleep stage 2 that underlies ultradian sleep regulation.

[Indexed for MEDLINE]

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