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Sleep. 2016 May 1;39(5):1129-37. doi: 10.5665/sleep.5770.

K-Complexes: Interaction between the Central and Autonomic Nervous Systems during Sleep.

Author information

1
Center for Health Sciences, SRI International, Menlo Park, CA.
2
University of Pittsburgh School of Medicine, Pittsburgh, PA.
3
Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa.
4
Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia.

Abstract

STUDY OBJECTIVES:

To investigate the relationship between K-complexes (KCs) and cardiac functioning.

METHODS:

Forty healthy adolescents aged 16-22 y (19 females) participated in the study. Heart rate (HR) fluctuations associated with spontaneous and evoked KCs were investigated on two nights, one with (event-related potential night) and one without auditory tones presented across the night.

RESULTS:

There was a clear biphasic cardiac response to evoked and spontaneous KCs, with an initial acceleration in HR followed by a deceleration (P < 0.001). HR acceleration occurred immediately to KCs in response to tones presented in the first third of the interbeat interval, but was delayed a beat when the tone occurred later in the cardiac cycle (P < 0.05). Sex differences were also evident. Pretone baseline HR was higher, and the magnitude of the HR response was blunted and delayed, in female compared to male adolescents (P < 0.001). Also, pretone baseline HR was lower when a tone elicited a KC compared to when it did not (P < 0.001), suggesting that KCs are possibly more likely to be elicited by external stimuli in states of reduced cardiac activation.

CONCLUSIONS:

The strict dependency observed between KCs and cardiac control indicates a potential role of KCs in modulating the cardiovascular system during sleep. Sex differences in the KC-cardiac response indicate the sensitivity of this measure in capturing sex differences in cardiac regulatory physiology.

KEYWORDS:

K-complex; autonomic nervous system; cardiovascular; heart rate; sex differences; sleep

PMID:
26856907
PMCID:
PMC4835312
DOI:
10.5665/sleep.5770
[Indexed for MEDLINE]
Free PMC Article

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