Poor Sleep Moderates the Relationship Between Daytime Napping and Inflammation in Black and White Men

• NCJ Number: 252886
• Journal: Sleep Health Volume: 3 Issue: 5 Dated: October 2017 Pages: 328-335
• Author(s): Karen P. Jakubowski; Jennifer M. Boylan; Jenny M. Cundiff; Karen A. Matthews
• Date Published: October 2017
• Length: 8 pages
• Grant Number(s): 96-MU-FX-0012
• Sponsoring Agency: Office of Juvenile Justice and Delinquency Prevention (OJJDP)
• Publication Format: Article
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored); Program/Project Description
• Language: English
• Country: United States of America

Annotation

This study tested whether napping was associated with two inflammatory markers with known relationships to cardiovascular disease: high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6).

Abstract

Because IL-6 is known to impact central inflammatory processes that relate to sleep regulation, including subjective fatigue, this study tested whether this relationship was moderated by sleep duration, sleep efficiency, and self-reported sleep quality. Using a cross-sectional design, a community sample of Black and White men (N = 253) completed a week of actigraphy and diary measures of sleep and napping and provided a fasting blood sample. Napping was measured as the proportion of days with at least 30 minutes napped and the average minutes napped per day. Linear regressions adjusted for race, socioeconomic status, employment, body mass index, smoking, medications that affect sleep or inflammation, working the nightshift, and day-sleeping status, followed by interaction terms between napping and sleep duration, efficiency, and quality, respectively. The study did not find any significant main effects of actigraphy- or diary-measured napping on IL-6 or hsCRP. Moderation analyses indicated elevated IL-6 values among men who napped more days (by actigraphy) and demonstrated short sleep duration (P = .03). Moderation analyses also indicated elevated IL-6 among men who demonstrated greater average minutes napped (by actigraphy) and short sleep duration (P < .001), low efficiency (P = .03), and poor quality (P = .03). Moderation analyses involving diary napping or hsCRP were not significant. The study's overall conclusion is that actigraphy-assessed daytime napping is related to higher IL-6 in men who demonstrate worse sleep characteristics. Daytime napping may pose additional risk for inflammation beyond the known risk conferred by short sleep.(publisher abstract modified)