Association of bedtime with mortality and major cardiovascular events: an analysis of 112,198 individuals from 21 countries in the PURE study.

Affiliation

Wang C(1), Hu B(1), Rangarajan S(2), Bangdiwala SI(2), Lear SA(3), Mohan V(4), Gupta R(5), Alhabib KF(6), Soman B(7), Abat MEM(8), Rosengren A(9), Lanas F(10), Avezum A(11), Lopez-Jaramillo P(12), Diaz R(13), Yusoff K(14), Iqbal R(15), Chifamba J(16), Yeates K(17), Zatońska K(18), Kruger IM(19), Bahonar A(20), Yusufali A(21), Li W(22), Yusuf S(23); Prospective Urban Rural Epidemiology (PURE) study investigators.
Author information:
(1)Medical Research and Biometrics Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
(2)Population Health Research Institute, McMaster University, Hamilton, ON, Canada.
(3)Faculty of Health Sciences, Simon Fraser University, Canada.
(4)Dr.Mohan's Diabetes Specialities Centre, No. 6, Conran Smith Road, Gopalapuram, Chennai 600086, India.
(5)Eternal Heart Care Centre & Research Institute, Jawahar Circle, Jaipur 302017, India.
(6)Department of Cardiac Sciences, King Fahad Cardiac Center, College of Medicine, King Saud University, Riyadh 11472, Saudi Arabia.
(7)Health Action By People, Navarangam Lane, Opp. Men's Hostel-3, Medical College, Trivandrum 695011, Kerala, India; Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, Kerala, India.
(8)Division of Adult Medicine, Department of Medicine, Philippine General Hospital, Republic of the Philippines.
(9)Sahlgrenska University Hospital/Östra Hospital, Diagnosvägen 11, SE 416 85 Göteborg, Sweden.
(10)Universidad de La Frontera, M Montt 112 Temuco, Chile.
(11)Hospital Alemão Oswaldo Cruz and UNISA, Rua 13 de Maio, 1975, São Paulo, SP, Brazil.
(12)Masira Research Institute, Universidad de Santander
(UDES), Colombia.
(13)Instituto Cardiovascular de Rosario, ECLA, Paraguay 160, 2000 Rosario, Argentina.
(14)Universiti Teknologi MARA, Jalan Prima Selayang 7, 68100 Batu Caves, Selangor, Malaysia; UCSI University, 1 Jalan Menara Gading, Taman Connaught, 56000 Cheras, Kuala Lumpur, Malaysia.
(15)Department of Community Health Sciences, The Aga Khan University, P.O. Box 3500 Stadium Road, Karachi 74800, Pakistan.
(16)University of Zimbabwe, Department of Physiology, P.O.Box MP167 Harare, Zimbabwe.
(17)Queen's University, Department of Medicine, Kingston, Ontario, Canada.
(18)Faculty of Medicine, Head of Social Medicine Department, Wroclaw Medical University, Bujwida 44 St, 50-345 Wroclaw, EU, Poland.
(19)Africa Unit for Transdisciplinary Health Research
(AUTHeR), North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, 2520, South Africa.
(20)Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran.
(21)Hatta Hospital, Dubai Medical College, Dubai Health Authority, Dubai, United Arab Emirates.
(22)Medical Research and Biometrics Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China. Electronic address: [Email]
(23)Population Health Research Institute, McMaster University, Hamilton, ON, Canada. Electronic address: [Email]

Abstract

OBJECTIVES: This study aimed to examine the association of bedtime with mortality and major cardiovascular events. METHODS: Bedtime was recorded based on self-reported habitual time of going to bed in 112,198 participants from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study. Participants were prospectively followed for 9.2 years. We examined the association between bedtime and the composite outcome of all-cause mortality, non-fatal myocardial infarction, stroke and heart failure. Participants with a usual bedtime earlier than 10PM were categorized as 'earlier' sleepers and those who reported a bedtime after midnight as 'later' sleepers. Cox frailty models were applied with random intercepts to account for the clustering within centers. RESULTS: A total of 5633 deaths and 5346 major cardiovascular events were reported. A U-shaped association was observed between bedtime and the composite outcome. Using those going to bed between 10PM and midnight as the reference group, after adjustment for age and sex, both earlier and later sleepers had a higher risk of the composite outcome (HR of 1.29 [1.22, 1.35] and 1.11 [1.03, 1.20], respectively). In the fully adjusted model where demographic factors, lifestyle behaviors (including total sleep duration) and history of diseases were included, results were greatly attenuated, but the estimates indicated modestly higher risks in both earlier (HR of 1.09 [1.03-1.16]) and later sleepers (HR of 1.10 [1.02-1.20]). CONCLUSION: Early (10 PM or earlier) or late (Midnight or later) bedtimes may be an indicator or risk factor of adverse health outcomes.