Daytime napping and increased risk of incident respiratory diseases: symptom, marker, or risk factor?
We have identified a strong association between daytime napping and increased mortality risk from respiratory diseases, but little is known about the relationship between daytime napping and respiratory morbidity.



Data were drawn from the European Prospective Investigation into Cancer and Nutrition-Norfolk cohort. Participants reported napping habits during 1998-2000 and were followed up for respiratory disease hospital admissions until March 2009. Cox proportional hazards regression was used to examine the association between daytime napping and respiratory disease incidence risk.



The study sample included 10,978 men and women with a mean age of 61.9 years, and a total of 946 incident respiratory disease cases were recorded. After adjustment for age, sex, social class, education, marital status, employment status, nightshift work, body mass index, physical activity, smoking, alcohol intake, self-reported general health, hypnotic drug use, habitual sleep duration, and preexisting health conditions, daytime napping was associated with an increase in the overall respiratory disease incidence risk (hazard ratio (HR) = 1.32, 95% confidence interval (CI) 1.15, 1.52 for napping <1 h; HR = 1.54, 95% CI 1.14, 2.09 for napping ≥1 h). This association was more pronounced for lower respiratory diseases, especially for the risk of chronic lower respiratory diseases (HR = 1.52, 95% CI: 1.18, 1.96 for napping <1 h; HR = 1.72, 95% CI: 1.01, 2.92 for napping ≥1 h, overall p = 0.003).



Excessive daytime napping might be a useful marker of future respiratory disease incidence risk. Further studies are required to confirm these findings and help understand potential mechanisms.
Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK. Electronic address: yue.leng@ucsf.edu.
Yue
Y
Leng
Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK.
Nick W J
NW
Wainwright
Division of Mental Health & Wellbeing, Warwick Medical School, University of Warwick, Coventry, UK.
Francesco P
FP
Cappuccio
Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK.
Paul G
PG
Surtees
Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK.
Shabina
S
Hayat
Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK.
Robert
R
Luben
Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge, UK.
Carol
C
Brayne
Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK.
Kay-Tee
KT
Khaw
D015415:Biomarkers; D005260:Female; D006184:Habits; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012120:Respiration Disorders / Q000453:epidemiology / Q000209:etiology / Q000523:psychology*; D012307:Risk Factors; D012890:Sleep
D015415:Biomarkers
Cohort study; Incidence; Napping; Respiratory; Sleep
Sleep Med. 2015 Jul;16(7):811-9
26051864
Am J Epidemiol. 2013 Sep 15;178(6):956-61
23801012
Sleep. 2006 Nov;29(11):1463-8
17162994
BMJ Open. 2014 Nov 11;4(11):e006071
25387759
Sleep. 1997 Sep;20(9):705-6
9406321
Psychosom Med. 2007 Nov;69(8):756-61
17942834
Br J Cancer. 1999 Jul;80 Suppl 1:95-103
10466767
JAMA. 2003 May 7;289(17):2230-7
12734134
Eur Respir J. 1996 Oct;9(10):2132-8
8902479
J Allergy Clin Immunol. 2003 Nov;112(5):819-27; quiz 828
14610463
Arch Intern Med. 2002 Apr 22;162(8):893-900
11966340
Am J Respir Crit Care Med. 2013 Feb 15;187(4):347-65
22878278
Eur Respir Rev. 2013 Sep 1;22(129):365-75
23997063
Sleep Med. 2015 Jul;16(7):809-10
25772544
Am J Epidemiol. 2014 May 1;179(9):1115-24
24685532
Sleep. 2012 Jan 01;35(1):97-101
22215923
BMJ. 2000 Feb 19;320(7233):479-82
10678860