Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men

Abstract During nocturnal sleep, core body temperature (CBT) decreases and cardiac inter‐beat intervals (IBI) increase. This study used a non‐disturbing cooling intervention during sleep to investigate additional effects of CBT reduction on IBI and heart rate variability. Sleep on a high heat‐capaci...

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Main Authors: Kurt Kräuchi, Martin Glos, Ingo Fietze, Thomas Penzel, Matteo Mason, Sebastian Herberger
Format: Article
Language:English
Published: Wiley 2025-08-01
Series:Physiological Reports
Subjects:
Online Access:https://doi.org/10.14814/phy2.70478
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author Kurt Kräuchi
Martin Glos
Ingo Fietze
Thomas Penzel
Matteo Mason
Sebastian Herberger
author_facet Kurt Kräuchi
Martin Glos
Ingo Fietze
Thomas Penzel
Matteo Mason
Sebastian Herberger
author_sort Kurt Kräuchi
collection DOAJ
description Abstract During nocturnal sleep, core body temperature (CBT) decreases and cardiac inter‐beat intervals (IBI) increase. This study used a non‐disturbing cooling intervention during sleep to investigate additional effects of CBT reduction on IBI and heart rate variability. Sleep on a high heat‐capacity cooling gel mattress (HM) was compared to a low heat‐capacity mattress (LM) in 32 healthy males (age 46 ± 4 years). Electroencephalography, electrocardiography, CBT, skin, mattress, and air temperatures were recorded under constant conditions. Power in the low‐ (LF) and high‐frequency (HF) bands and the LF/HF ratio were calculated from one‐minute IBI intervals. Sleep on HM led to greater CBT decline and showed increased IBI and HF in all sleep stages. Mediation analyses indicate HF is not directly influenced by CBT, but HF changes follow IBI, which mediates CBT effects on HF. HF and LF differ between sleep stages: HF is lower during rapid eye movement (REM) and higher during non‐REM, independent of CBT or IBI. In sum, sleep on a cooling mattress decreases CBT, which increases IBI and HF, independent of sleep stages. Cooling‐induced HF changes are mediated by IBI. In contrast, HF and LF vary with sleep stages, reflecting autonomic activity throughout sleep cycles, independent of thermophysiological changes.
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spelling doaj-art-a9aa22fe4fae4bceaf0b71772d18a4f92025-08-20T03:44:14ZengWileyPhysiological Reports2051-817X2025-08-011315n/an/a10.14814/phy2.70478Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy menKurt Kräuchi0Martin Glos1Ingo Fietze2Thomas Penzel3Matteo Mason4Sebastian Herberger5Psychiatric University Clinics University of Basel Basel SwitzerlandInterdisciplinary Center of Sleep Medicine Charité – Universitätsmedizin Berlin Berlin GermanyInterdisciplinary Center of Sleep Medicine Charité – Universitätsmedizin Berlin Berlin GermanyInterdisciplinary Center of Sleep Medicine Charité – Universitätsmedizin Berlin Berlin GermanyTechnogel Italia S.R.L. Vicenza ItalyInterdisciplinary Center of Sleep Medicine Charité – Universitätsmedizin Berlin Berlin GermanyAbstract During nocturnal sleep, core body temperature (CBT) decreases and cardiac inter‐beat intervals (IBI) increase. This study used a non‐disturbing cooling intervention during sleep to investigate additional effects of CBT reduction on IBI and heart rate variability. Sleep on a high heat‐capacity cooling gel mattress (HM) was compared to a low heat‐capacity mattress (LM) in 32 healthy males (age 46 ± 4 years). Electroencephalography, electrocardiography, CBT, skin, mattress, and air temperatures were recorded under constant conditions. Power in the low‐ (LF) and high‐frequency (HF) bands and the LF/HF ratio were calculated from one‐minute IBI intervals. Sleep on HM led to greater CBT decline and showed increased IBI and HF in all sleep stages. Mediation analyses indicate HF is not directly influenced by CBT, but HF changes follow IBI, which mediates CBT effects on HF. HF and LF differ between sleep stages: HF is lower during rapid eye movement (REM) and higher during non‐REM, independent of CBT or IBI. In sum, sleep on a cooling mattress decreases CBT, which increases IBI and HF, independent of sleep stages. Cooling‐induced HF changes are mediated by IBI. In contrast, HF and LF vary with sleep stages, reflecting autonomic activity throughout sleep cycles, independent of thermophysiological changes.https://doi.org/10.14814/phy2.70478body coolingbody temperaturecooling mattressheart rate‐variabilityinterbeat intervalsleep stages
spellingShingle Kurt Kräuchi
Martin Glos
Ingo Fietze
Thomas Penzel
Matteo Mason
Sebastian Herberger
Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men
Physiological Reports
body cooling
body temperature
cooling mattress
heart rate‐variability
interbeat interval
sleep stages
title Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men
title_full Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men
title_fullStr Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men
title_full_unstemmed Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men
title_short Slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high‐frequency heart rate variability in healthy men
title_sort slow nocturnal body cooling during sleep increases interbeat intervals and is tightly coupled to high frequency heart rate variability in healthy men
topic body cooling
body temperature
cooling mattress
heart rate‐variability
interbeat interval
sleep stages
url https://doi.org/10.14814/phy2.70478
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