Sleep: Another benefit of regular sleep
A large observational study has found that irregular sleep-wake patterns are associated with a higher risk of overall mortality, and also mortality from cancers and cardiovascular disease.
- Channing Division of Network Medicine, Brigham and Women’s Hospital and Harvard Medical School, United States
- Division of Sleep Medicine, Harvard Medical School, United States
Benjamin Franklin’s famous quotation – “Early to bed and early to rise makes a man healthy, wealthy, and wise” – underscores the importance of sleep-wake patterns to our health and well-being. Of all the phenomena that are influenced by the 24 hour light-dark cycle, the sleep-wake cycle is the best known, but many other biological processes central to health are also influenced. However, empirical evidence about the impact that disruptions to sleep-wake patterns have on human health remains sparse and is mostly limited to studies on shift workers, despite an increase in other forms of disruption (notably higher levels of artificial light at night and increased use of mobile media in bed).
In recent years, an increasing number of studies have looked at the impact of sleep regularity (and irregularity) on aspects of health besides sleep quantity and quality, often made possible by the availability of wearable technology that is able to monitor rest-activity cycles in large numbers of people. Studies have found evidence that sleep irregularity is associated with a higher incidence of obesity (Patel et al., 2014), depression (Fang et al., 2021), cardiovascular disease (Huang et al., 2020) and other chronic disease outcomes.
Now, in eLife, Matthew Pase, Andree-Ann Baril and colleagues – including Lachlan Cribb, Ramon Sha and Stephanie Yiallourou, all of Monash University, as joint first authors – go one step further by linking sleep regularity with all-cause and cause-specific mortality in a large UK population (Cribb et al., 2023). Between 2013 and 2015, a total of more than 106,000 participants in the UK wore a watch-like device called an accelerometer over seven consecutive days. Based on the signals from this device it was possible to tell when the participants were asleep, sedentary, or active. Cribb et al. then derived a novel metric called the Sleep Regularity Index (SRI) to quantify day-to-day consistency in sleep-wake schedules. This metric is an estimate of how likely it is that a person is in the same state (that is, either awake or asleep) at any two time points 24 hours apart, with higher SRI values indicating higher sleep regularity. The researchers also noted how many of the participants subsequently died (via data from the UK national death register).
Over a median follow-up of 7.1 years, some 3,010 participants died, with 1,701 of these deaths being due to cancers and 616 being due to cardiovascular disease. Compared with those who had a medium SRI value, the top 5% (that is, the most regular sleepers) had 10% lower all-cause mortality, and the bottom 5% (that is, the most irregular sleepers) had 53% higher mortality. The association appeared nonlinear, with stronger associations observed for the increased mortality with more irregular sleep. Similar nonlinear patterns were observed when Cribb et al. examined cancer mortality and cardiovascular disease mortality separately.
The work by Cribb et al. is consistent with recent studies on sleep regularity and mortality from the US and Japan, although these findings are based on a smaller sample size (Chung et al., 2023a) or on self-reported sleep regularity (Omichi et al., 2022). Other studies found that sleep regularity was a stronger predictor for mortality than sleep duration or sleep apnea (Chung et al., 2023b; Windred et al., 2023). Interestingly, a genome-wide association study for sleep traits (Jones et al., 2019) reported a heritability estimate of 2.8% for sleep regularity, compared with 19.0% for sleep duration and 22.3% for fragmented sleep: this suggests that it may be easier to modify sleep regularity via interventions than it would be to modify other sleep traits because sleep regularity is less genetically determined.
Promoting sleep regularity is not a new idea in the area of ‘sleep hygiene’, and encouraging regular sleep schedules is also an essential component in cognitive behavioral therapy for insomnia (Sletten et al., 2023). From the behavioral perspective, promoting sleep regularity may also enhance the time-of-day effect of other behaviors, such as time-restricted eating and exercise. However, promoting sleep regularity for broader health promotion and disease prevention has not been tested in intervention studies and requires additional evidence from future investigations.
In summary, the study by Cribb et al. adds to the emerging evidence for the potential benefits of sleep regularity on chronic disease risk and mortality. The findings, in conjunction with prior evidence, provide a strong foundation to answer the following question: would public health interventions to improve sleep regularity causally lead to reductions in chronic disease and premature deaths at the population level?
References
-
Sleep irregularity and risk of cardiovascular events: The Multi-Ethnic Study of AtherosclerosisJournal of the American College of Cardiology 75:991–999.https://doi.org/10.1016/j.jacc.2019.12.054
-
The association between sleep patterns and obesity in older adultsInternational Journal of Obesity 38:1159–1164.https://doi.org/10.1038/ijo.2014.13
Article and author information
Author details
Publication history
- Version of Record published: December 1, 2023 (version 1)
Copyright
© 2023, Huang
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 240
- Page views
-
- 30
- Downloads
-
- 0
- Citations
Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Sleep: Another benefit of regular sleep
eLife 12:e94131.
https://doi.org/10.7554/eLife.94131
Further reading
-
- Epidemiology and Global Health
- Medicine
Background:
Although there are several efficacious vaccines against COVID-19, vaccination rates in many regions around the world remain insufficient to prevent continued high disease burden and emergence of viral variants. Repurposing of existing therapeutics that prevent or mitigate severe COVID-19 could help to address these challenges. The objective of this study was to determine whether prior use of bisphosphonates is associated with reduced incidence and/or severity of COVID-19.
Methods:
A retrospective cohort study utilizing payer-complete health insurance claims data from 8,239,790 patients with continuous medical and prescription insurance January 1, 2019 to June 30, 2020 was performed. The primary exposure of interest was use of any bisphosphonate from January 1, 2019 to February 29, 2020. Bisphosphonate users were identified as patients having at least one bisphosphonate claim during this period, who were then 1:1 propensity score-matched to bisphosphonate non-users by age, gender, insurance type, primary-care-provider visit in 2019, and comorbidity burden. Main outcomes of interest included: (a) any testing for SARS-CoV-2 infection; (b) COVID-19 diagnosis; and (c) hospitalization with a COVID-19 diagnosis between March 1, 2020 and June 30, 2020. Multiple sensitivity analyses were also performed to assess core study outcomes amongst more restrictive matches between BP users/non-users, as well as assessing the relationship between BP-use and other respiratory infections (pneumonia, acute bronchitis) both during the same study period as well as before the COVID outbreak.
Results:
A total of 7,906,603 patients for whom continuous medical and prescription insurance information was available were selected. A total of 450,366 bisphosphonate users were identified and 1:1 propensity score-matched to bisphosphonate non-users. Bisphosphonate users had lower odds ratios (OR) of testing for SARS-CoV-2 infection (OR = 0.22; 95%CI:0.21–0.23; p<0.001), COVID-19 diagnosis (OR = 0.23; 95%CI:0.22–0.24; p<0.001), and COVID-19-related hospitalization (OR = 0.26; 95%CI:0.24–0.29; p<0.001). Sensitivity analyses yielded results consistent with the primary analysis. Bisphosphonate-use was also associated with decreased odds of acute bronchitis (OR = 0.23; 95%CI:0.22–0.23; p<0.001) or pneumonia (OR = 0.32; 95%CI:0.31–0.34; p<0.001) in 2019, suggesting that bisphosphonates may protect against respiratory infections by a variety of pathogens, including but not limited to SARS-CoV-2.
Conclusions:
Prior bisphosphonate-use was associated with dramatically reduced odds of SARS-CoV-2 testing, COVID-19 diagnosis, and COVID-19-related hospitalizations. Prospective clinical trials will be required to establish a causal role for bisphosphonate-use in COVID-19-related outcomes.
Funding:
This study was supported by NIH grants, AR068383 and AI155865, a grant from MassCPR (to UHvA) and a CRI Irvington postdoctoral fellowship, CRI2453 (to PH).
-
- Epidemiology and Global Health
Background:
The Coronavirus Disease of 2019 (COVID-19) has impacted the health and day-to-day life of individuals, especially the elderly and people with certain pre-existing medical conditions, including cancer. The purpose of this study was to investigate how COVID-19 impacted access to cancer screenings and treatment, by studying the participants in the Multiethnic Cohort (MEC) study.
Methods:
The MEC has been following over 215,000 residents of Hawai‘i and Los Angeles for the development of cancer and other chronic diseases since 1993–1996. It includes men and women of five racial and ethnic groups: African American, Japanese American, Latino, Native Hawaiian, and White. In 2020, surviving participants were sent an invitation to complete an online survey on the impact of COVID-19 on their daily life activities, including adherence to cancer screening and treatment. Approximately 7,000 MEC participants responded. A cross-sectional analysis was performed to investigate the relationships between the postponement of regular health care visits and cancer screening procedures or treatment with race and ethnicity, age, education, and comorbidity.
Results:
Women with more education, women with lung disease, COPD, or asthma, and women and men diagnosed with cancer in the past 5 years were more likely to postpone any cancer screening test/procedure due to the COVID-19 pandemic. Groups less likely to postpone cancer screening included older women compared to younger women and Japanese American men and women compared to White men and women.
Conclusions:
This study revealed specific associations of race/ethnicity, age, education level, and comorbidities with the cancer-related screening and healthcare of MEC participants during the COVID-19 pandemic. Increased monitoring of patients in high-risk groups for cancer and other diseases is of the utmost importance as the chance of undiagnosed cases or poor prognosis is increased as a result of delayed screening and treatment.
Funding:
This research was partially supported by the Omidyar 'Ohana Foundation and grant U01 CA164973 from the National Cancer Institute.
