Terry B J Kuo1, Cian-Hui Hong2, I-Te Hsieh3, Guo-She Lee4, Cheryl C H Yang5. 1. Sleep Research Center, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Biophotonics, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan. 2. Sleep Research Center, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan. 3. Sleep Research Center, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Biophotonics, School of Medicine, National Yang-Ming University, Taipei, Taiwan. 4. Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan. 5. Sleep Research Center, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan. Electronic address: cchyang@ym.edu.tw.
Abstract
BACKGROUND: Various studies have linked the occurrence of cardiovascular events and low ambient temperatures as well as the morning blood pressure surge (MBPS). We hypothesized that low ambient temperatures produce a higher sympathetic change during the last rapid eye movement (REM) sleep transition and that this may play an important role in cold-related cardiovascular events. METHODS: All experiments were carried out on 12 healthy male adults, aged 24.00±0.74 years, who participated in two experimental conditions randomly (>1 day apart): warm (23 °C) and cold (16°C). Blood pressure (BP) was measured every 30 min for 24 h by autonomic ambulatory BP monitoring. The electroencephalograms, electrocardiograms, ambient temperature, near-body temperature, and physical activity were recorded by miniature polysomnography for 24 h. RESULTS: The cold conditions resulted in: (i) higher MBPS than under warm conditions; (ii) significant and greater sympathetic index changes during the sleep-wake transition than during cover-to-uncover and supine-to-sit position tests; (iii) the non-REM-REM transition-related sympathetic elevation during the cold conditions being significantly higher in late sleep period than in early sleep period; (iv) at 1h prior to morning awakening, the value of total power of heart rate variability changes being significantly negatively correlated with the changes of near-body temperature; and (v) significantly higher arousal index and shorter average interval of REM periods than in warm conditions. CONCLUSION:Cold exposure elevates the amplitude of MBPS and is associated with late sleep stage transition sympathetic activation, which might have important implications for cold-related cardiovascular events.
RCT Entities:
BACKGROUND: Various studies have linked the occurrence of cardiovascular events and low ambient temperatures as well as the morning blood pressure surge (MBPS). We hypothesized that low ambient temperatures produce a higher sympathetic change during the last rapid eye movement (REM) sleep transition and that this may play an important role in cold-related cardiovascular events. METHODS: All experiments were carried out on 12 healthy male adults, aged 24.00±0.74 years, who participated in two experimental conditions randomly (>1 day apart): warm (23 °C) and cold (16°C). Blood pressure (BP) was measured every 30 min for 24 h by autonomic ambulatory BP monitoring. The electroencephalograms, electrocardiograms, ambient temperature, near-body temperature, and physical activity were recorded by miniature polysomnography for 24 h. RESULTS: The cold conditions resulted in: (i) higher MBPS than under warm conditions; (ii) significant and greater sympathetic index changes during the sleep-wake transition than during cover-to-uncover and supine-to-sit position tests; (iii) the non-REM-REM transition-related sympathetic elevation during the cold conditions being significantly higher in late sleep period than in early sleep period; (iv) at 1h prior to morning awakening, the value of total power of heart rate variability changes being significantly negatively correlated with the changes of near-body temperature; and (v) significantly higher arousal index and shorter average interval of REM periods than in warm conditions. CONCLUSION: Cold exposure elevates the amplitude of MBPS and is associated with late sleep stage transition sympathetic activation, which might have important implications for cold-related cardiovascular events.
Authors: Cian-Hui Hong; Terry B J Kuo; Bo-Chi Huang; Yu-Cheng Lin; Kuan-Liang Kuo; Chang-Ming Chern; Cheryl C H Yang Journal: PLoS One Date: 2016-02-26 Impact factor: 3.240