Two new observational studies have highlighted some possible health advantages of regularly getting a good night’s (rather than day’s) sleep.
The first reports that adults with the healthiest sleep patterns have a lower risk of heart failure, regardless of other risk factors, while the second suggests that permanent night shift workers have heightened risk of moderate to severe asthma.
Both made use of data from the UK Biobank, which is following the long-term health and wellbeing of 500,000 volunteer participants.
The heart study, led by Tulane University in the US, looked at 408,802 participants aged 37 to 73 at the time of recruitment.
The researchers found that, after adjusting for diabetes, hypertension, medication use, genetic variations and other covariates, participants with the healthiest sleep patterns, as assessed by key behaviours, were found to have a 42% lower risk of heart failure.
And each behaviour had its independent value. Risk was found to be 8% lower in early risers, 12% lower in those who slept seven to eight hours daily, 17% lower in those who did not have frequent insomnia, and 34% lower in those reporting no daytime sleepiness.
The findings are published in the American Heart Association journal Circulation.
The researchers acknowledge some limitations to the study: sleep behaviours were self-reported, information on changes in sleep behaviours during follow-up were not available, and other unmeasured or unknown adjustments may have influenced the findings.
Nevertheless, the results “highlight the importance of improving overall sleep patterns to help prevent heart failure”, says corresponding author Lu Qi.
The second study, published in the journal Thorax, followed 286,825 Biobank participants aged 37 to 72; 14,238 (around 5%) had asthma, 4783 of them (nearly 2%) with moderate to severe based on their medications.
The researchers, led by the University of Manchester, UK, compared the effect of working office hours with shift work on asthma diagnosis, lung function, and symptoms of asthma.
After taking account of age and sex, and a wide range of other potentially influential risk factors, there was found to be a 36% increase in the odds of having moderate to severe asthma in permanent night shift workers compared to those working normal office hours.
Those who were “extreme chronotypes” – having body clock preferences for morning or evening activity – were significantly more likely to have asthma, even after taking account of a range of potentially influential risk factors.
The odds of moderate to severe asthma were 55% higher among morning people working irregular shifts, including nights.
Genetic susceptibility to asthma didn’t affect the odds of developing asthma among those working shifts, however.