{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,19]],"date-time":"2026-09-19T05:01:55Z","timestamp":1789794115950,"version":"4.0.1"},"reference-count":29,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T00:00:00Z","timestamp":1789516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Study Objectives: While the pathophysiology of Narcolepsy Type 1 (NT1) involves hypocretin deficiency, the microstructural electrophysiological features that distinguish NT1 from Narcolepsy Type 2 (NT2) remain incompletely defined. This study evaluated sleep microstructure with a six-subtype K-complex (KC) categorization (G\u00fclhane Classification). Methods: Retrospective polysomnography from the December 2016\u2013January 2026 clinical archive was reviewed. K-complex scoring defined the analyzed sample: NT1 n = 18, NT2 n = 13, and simple-snoring controls with AHI &lt; 5 (n = 15). Complete overnight PSG summaries were available for NT1 n = 16 and NT2 n = 13. Six visually defined KC subtypes (Isolated-KC, KC-Burst, KC-Sigma, KC-Delta, Polyphasic-KC, and Polyphasic-KC-Sigma) were compared across Descendant, Intermediate, and Ascendant portions of the NREM cycle. Results: Compared with controls, NT1 showed lower Isolated-KC and KC-Sigma counts across cycle periods (p &lt; 0.05). NT1 also had higher wake after sleep onset (WASO; 34.7 \u00b1 21.1 min) and lower sleep efficiency (90.7 \u00b1 5.4%) than NT2. NT1\u2013NT2 differences that reached p &lt; 0.05 were KC-Delta in the Intermediate (p = 0.015) and Descendant (p = 0.030) periods, Isolated-KC in the Intermediate period (p = 0.039), and KC-Sigma in the Descendant period (p = 0.041). Conclusions: In this retrospective cohort, morphological KC subtyping showed a coherent reduction in Isolated-KC and KC-Sigma in NT1. The findings are descriptive and require prospective validation; they do not constitute a standalone diagnostic test.<\/jats:p>","DOI":"10.3390\/life16091556","type":"journal-article","created":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T16:07:29Z","timestamp":1789574849000},"page":"1556","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A New Electrophysiological Approach to Sleep Microstructure: The G\u00fclhane Classification of K-Complex Subtypes in Narcolepsy Type 1 and Type 2"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6605-0367","authenticated-orcid":false,"given":"Volkan","family":"Tekin","sequence":"first","affiliation":[{"name":"Department of Physiology, G\u00fclhane Faculty of Medicine, University of Health Sciences, 06010 Ankara, T\u00fcrkiye"},{"name":"Sleep Research Center, Department of Psychiatry, G\u00fclhane Education and Research Hospital, 06010 Ankara, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mehmet","family":"Ko\u00e7er","sequence":"additional","affiliation":[{"name":"Sleep Research Center, Department of Psychiatry, G\u00fclhane Education and Research Hospital, 06010 Ankara, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Esra","family":"\u00dcnverdi-B\u0131\u00e7ak\u00e7\u0131","sequence":"additional","affiliation":[{"name":"Sleep Research Center, Department of Psychiatry, G\u00fclhane Education and Research Hospital, 06010 Ankara, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fulya","family":"\u015eahin","sequence":"additional","affiliation":[{"name":"Sleep Research Center, Department of Psychiatry, G\u00fclhane Education and Research Hospital, 06010 Ankara, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B\u00fclent Devrim","family":"Ak\u00e7ay","sequence":"additional","affiliation":[{"name":"Sleep Research Center, Department of Psychiatry, G\u00fclhane Education and Research Hospital, 06010 Ankara, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sinan","family":"Yetkin","sequence":"additional","affiliation":[{"name":"Sleep Research Center, Department of Psychiatry, G\u00fclhane Education and Research Hospital, 06010 Ankara, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1152\/jn.1938.1.5.413","article-title":"Distribution of disturbance-patterns in the human electroencephalogram with special reference to sleep","volume":"1","author":"Loomis","year":"1938","journal-title":"J. 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