Spontaneous K-Complex Density in Slow-Wave Sleep

Md Dilshad Manzar; Mohammad Muntafa Rajput; Wassilatul Zannat; Seithikurippu R Pandi-Perumal; Ahmed S BaHammam; M Ejaz Hussain

doi:10.1371/journal.pone.0150929

Spontaneous K-Complex Density in Slow-Wave Sleep

PLoS One. 2016 Mar 10;11(3):e0150929. doi: 10.1371/journal.pone.0150929. eCollection 2016.

Authors

Md Dilshad Manzar^{1

2}, Mohammad Muntafa Rajput³, Wassilatul Zannat¹, Seithikurippu R Pandi-Perumal⁴, Ahmed S BaHammam⁵, M Ejaz Hussain¹

Affiliations

¹ Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, New Delhi, India.
² Department of Biomedical Science, College of Health Science, Mizan Tepi University, Mizan Teferi, Ethiopia.
³ Department of Biochemistry, Institute of Home Economics, University of Delhi, New Delhi, India.
⁴ Somnogen Canada Inc., College Street, Toronto, Canada.
⁵ The University Sleep Disorders Center, Department of Medicine, College of Medicine, and NSTIP Strategic Technologies Program, College of Medicine, King Saud University, Riyadh, Saudi Arabia.

Abstract

Purpose: To study spontaneous K-complex (KC) densities during slow-wave sleep. The secondary objective was to estimate intra-non-rapid eye movement (NREM) sleep differences in KC density.

Materials and methods: It is a retrospective study using EEG data included in polysomnographic records from the archive at the sleep research laboratory of the Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, India. The EEG records of 4459 minutes were used. The study presents a manual identification investigation of KCs in 17 healthy young adult male volunteers (age = 23.82±3.40 years and BMI = 23.42±4.18 kg/m2).

Results: N3 had a higher KC density than N2 (Z = -2.485, p = 0.013) for all of the probes taken together. Four EEG probes had a higher probe-specific KC density during N3. The inter-probe KC density differed significantly during N2 (χ2 = 67.91, p < .001), N3 (χ2 = 70.62, p < .001) and NREM (χ2 = 68.50, p < .001). The percent distribution of KC decreased uniformly with sleep cycles.

Conclusion: The inter-probe differences during N3 establish the fronto-central dominance of the KC density regardless of sleep stage. This finding supports one local theory of KC generation. The significantly higher KC density during N3 may imply that the neuro-anatomical origin of slow-wave activity and KC is the same. This temporal alignment with slow-wave activity supports the sleep-promoting function of the KC.

Publication types

Clinical Trial
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Electroencephalography*
Humans
Male
Sleep Stages / physiology*

Grants and funding

The grants-3/1/JRF-2007/MPD and 37-222/2009 (SR-) from the Indian Council of Medical Research (ICMR) and the University Grants Commission (UGC), respectively, funded the research. The funders had no role in the study design, data collection and analysis, preparation of the manuscript, or the decision to publish. This work was also supported by the Strategic Technologies Program of the National Plan for Sciences and Technology and Innovation in the Kingdom of Saudi Arabia. None of the study sponsors played any role in the study design, the collection, analysis or interpretation of data, writing the manuscript, or the decision to submit the manuscript. The funder provided support in the form of salaries for the authors [SRP] but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are described in the ‘author contributions’ section.