Long Sleep Duration and Midday Naps may Increase Stroke Risk

by | Feb 11, 2020 | 2020, Cardiovascular Health, Sleep, Stroke

Written by Joyce Smith, BS. Long sleep duration, long midday napping and poor sleep quality were independently and jointly associated with a higher risk of stroke.

Brain HealthMidday napping is a common practice in China and while evidence from previous studies have implied an association between length of sleep and stroke risk, only one study to date has investigated the impact of midday napping on the health of Chinese adults 1.  Previous studies have focused on long sleep duration and its association with elevated levels of inflammatory markers 2, unfavorable changes in lipid profiles 3, and metabolic syndrome 4. Also, adding to the stroke risk are sleep disorders such as obstructive sleep apnea 5, insomnia 6, and even depression 7. Thus the effect of midday naps, sleep duration, and sleep quality among Chinese adults remains to be elucidated.

Zhang and colleagues 8 analyzed data from the Dongfeng-Tongji cohort (DFTJ), a large, prospective cohort study of retired workers that explores the effects of related environment, occupational, lifestyle, and genetic factors, as well as their interactions on the etiology of major chronic diseases in a Chinese population. The team analyzed data from 31,750 DFTJ participants (mean age of  61.7 years to determine how the effects of sleep duration, midday napping, sleep quality, and changes in sleep duration impact the risk of incident stroke and stroke subtypes. All participants were stroke free with no major health issues at baseline and were followed for an average of 6 years. Self-administered questionnaires were used to assess sleep duration, midday napping and sleep quality. Incident stroke was determined by follow up questionnaires, physician diagnosis and hospital records. A total of 1,557 strokes were reported; 1,438 of the strokes were used to analyze stroke subtypes.

  • Sleeping nine or more hours per night and taking long midday naps of more than 90 minutes were shown to be significantly associated with an 85% higher risk of stroke (particularly ischemic stroke).
  • Compared to those who slept 7 or less than 8 hours per night, participants who slept 9 or more hours per night had a significantly greater risk (23%) of total stroke while sleeping less than 6 hours per night was not significantly associated with stroke risk.
  • Poor sleep quality was associated with a higher risk of total stroke and also associated separately with ischemic and hemorrhagic stroke. There were also significant joint effects of sleep duration and midday napping, and sleep duration and sleep quality on risk of total stroke. Sleeping for a persistent long duration (greater than 9 hours per night) and switching from 7-9 hours to greater than 9 hours per night also had a higher risk of stroke.
  • The risk of stroke with long sleep duration appeared to be more pronounced in participants who were 65 years of age or older or who had hypertension, hyperlipidemia or diabetes. Reduced work load or social activities in these participants may have contributed in part to their increased sleep and stroke risk, whereas, for those with hypertension, hyperlipidemia or diabetes, the increased risk of stroke may have also been biologically driven.

Study limitations include the use of a questionnaire which could greatly overestimate actual sleeping time rather than recording biological sleep. Using only middle-aged and older Chinese adults who were free of cancer and heart disease excludes generalization to other age groups of different ethnicities and health status. Furthermore, crude subjective measures rather than a validated screening questionnaire were used to evaluate sleep quality. However, the study does emphasize the importance of achieving good quality sleep of appropriate duration and with moderate midday napping to decrease risk of stroke, particularly in middle-aged and older adults.

Source: Zhou, Lue, Kuai Yu, Liangle Yang, Hao Wang, Yang Xiao, Gaokun Qiu, Xuezhen Liu et al. “Sleep duration, midday napping, and sleep quality and incident stroke: The Dongfeng-Tongji cohort.” Neurology 94, no. 4 (2020): e345-e356.

©2019 American College of Neurology

Posted February 11, 2020.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

  1. Li X, Pang X, Liu Z, et al. Joint effect of less than 1 h of daytime napping and seven to 8 h of night sleep on the risk of stroke. Sleep Med. 2018;52:180-187.
  2. Patel SR, Zhu X, Storfer-Isser A, et al. Sleep duration and biomarkers of inflammation. Sleep. 2009;32(2):200-204.
  3. Li L, Zhang S, Huang Y, Chen K. Sleep duration and obesity in children: A systematic review and meta‐analysis of prospective cohort studies. Journal of paediatrics and child health. 2017;53(4):378-385.
  4. Yang L, Xu Z, He M, et al. Sleep Duration and Midday Napping with 5-Year Incidence and Reversion of Metabolic Syndrome in Middle-Aged and Older Chinese. Sleep. 2016;39(11):1911-1918.
  5. Yaggi HK, Concato J, Kernan WN, Lichtman JH, Brass LM, Mohsenin V. Obstructive sleep apnea as a risk factor for stroke and death. The New England journal of medicine. 2005;353(19):2034-2041.
  6. Wu MP, Lin HJ, Weng SF, Ho CH, Wang JJ, Hsu YW. Insomnia subtypes and the subsequent risks of stroke: report from a nationally representative cohort. Stroke. 2014;45(5):1349-1354.
  7. Pan A, Sun Q, Okereke OI, Rexrode KM, Hu FB. Depression and risk of stroke morbidity and mortality: a meta-analysis and systematic review. Jama. 2011;306(11):1241-1249.
  8. Zhou L, Yu K, Yang L, et al. Sleep duration, midday napping, and sleep quality and incident stroke: The Dongfeng-Tongji cohort. Neurology. 2020;94(4):e345-e356.