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Inter-individual differences in the dynamics of sleep homeostasis


Rusterholz, T; Dürr, R; Achermann, P (2010). Inter-individual differences in the dynamics of sleep homeostasis. Sleep, 33(4):491-498.

Abstract

STUDY OBJECTIVES: The two-process model posits that sleep is regulated by 2 independent processes, a circadian Process C and a homeostatic Process S. EEG slow-wave activity (SWA) is a marker of NREM sleep intensity and is used as an indicator of sleep homeostasis. So far, parameters of the two-process model have been derived mainly from average data. Our aim was to quantify inter-individual differences. DESIGN: Polysomnographic recordings (analysis of existing data). SETTING: Sound attenuated sleep laboratory. PATIENTS OR PARTICIPANTS: Eight healthy young males. INTERVENTIONS: 40-h sustained wakefulness. MEASUREMENTS AND RESULTS: Process S was modeled by a saturating exponential function during wakefulness and an exponential decline during sleep. Empirical mean SWA (derivation C3A2) per NREM sleep episode at episode midpoint were used for parameter estimation. Parameters were estimated simultaneously by minimizing the mean square error between data and simulations of Process S. This approach was satisfactory for average data and most individual data. We further improved our methodological approach by limiting the time constants to a physiologically meaningful range. This allowed a satisfactory fit also for the one individual whose parameters were beyond a physiological range. The time constants of the buildup of Process S ranged from 14.1 h to 26.4 h and those of the decline from 1.2 h to 2.9 h with similar inter-individual variability of the buildup and decline of Process S. CONCLUSIONS: We established a robust method for parameter estimation of Process S on an individual basis.

STUDY OBJECTIVES: The two-process model posits that sleep is regulated by 2 independent processes, a circadian Process C and a homeostatic Process S. EEG slow-wave activity (SWA) is a marker of NREM sleep intensity and is used as an indicator of sleep homeostasis. So far, parameters of the two-process model have been derived mainly from average data. Our aim was to quantify inter-individual differences. DESIGN: Polysomnographic recordings (analysis of existing data). SETTING: Sound attenuated sleep laboratory. PATIENTS OR PARTICIPANTS: Eight healthy young males. INTERVENTIONS: 40-h sustained wakefulness. MEASUREMENTS AND RESULTS: Process S was modeled by a saturating exponential function during wakefulness and an exponential decline during sleep. Empirical mean SWA (derivation C3A2) per NREM sleep episode at episode midpoint were used for parameter estimation. Parameters were estimated simultaneously by minimizing the mean square error between data and simulations of Process S. This approach was satisfactory for average data and most individual data. We further improved our methodological approach by limiting the time constants to a physiologically meaningful range. This allowed a satisfactory fit also for the one individual whose parameters were beyond a physiological range. The time constants of the buildup of Process S ranged from 14.1 h to 26.4 h and those of the decline from 1.2 h to 2.9 h with similar inter-individual variability of the buildup and decline of Process S. CONCLUSIONS: We established a robust method for parameter estimation of Process S on an individual basis.

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15 citations in Web of Science®
17 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Pharmacology and Toxicology
04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2010
Deposited On:14 Jul 2010 18:57
Last Modified:05 Apr 2016 14:10
Publisher:Associated Professional Sleep Societies, LLC
ISSN:0161-8105
Free access at:PubMed ID. An embargo period may apply.
Official URL:http://www.journalsleep.org/ViewAbstract.aspx?pid=27749
PubMed ID:20394318
Permanent URL: https://doi.org/10.5167/uzh-34734

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