Poor quality sleep could double the risk from an individual’s genetic susceptibility to asthma, according to a study of the British population published today.
Researchers from Shandong University, Jinan, China, analysed 455,405 UK Biobank participants to establish if sleep quality influences asthma risk, or if healthy sleep patterns reduces the risk.
Bowen Xiang and colleagues drew on responses of the participants, all of whom were between 38 and 73 years old when they enrolled on the UK Biobank study between 2006 and 2010.
Participants were asked about their sleep patterns, based on five specific traits: early or late chronotype; sleep duration; insomnia; snoring; and excessive daytime sleepiness.
A healthy sleep pattern was defined as early chronotype; seven to nine hours of sleep every night; never or rare insomnia; no snoring; and no frequent daytime sleepiness.
Based on participants’ responses, 73,223 people met the criteria for a healthy sleep pattern, while 284,267 were classed as having an intermediate sleep pattern. A poor sleep pattern was allocated to 97,915 UK Biobank participants.
A genetic asthma risk score for each of the 455,405 people in the study was drawn up according to the number of genetic variants associated with asthma in their genome.
Writing in BMJ Open Respiratory Research, the researchers found that about one in three (150,429) were classed as having a “high” genetic risk, while another third (151,970) had an “intermediate” risk. The remainder were “low” risk.
Participants’ respiratory health was tracked up to the date of an asthma diagnosis, death, or until 31 March 2017, whichever came first.
During a monitoring period of just under nine years, 17,836 people were diagnosed with asthma and they were more likely to have potentially influential risk factors than those who did not, including lower levels of education and a greater likelihood of unhealthy sleep traits and patterns; obesity; higher genetic asthma risk scores; higher levels of smoking and drinking; and greater exposure to air pollution.
Out of the high genetic risk cohort, 7,105 people were diagnosed with asthma compared to 5,748 in the intermediate genetic risk category.
Compared with those at low genetic risk, individuals in the highest risk category were 47% more likely to be diagnosed with asthma, while those with a poor sleep pattern were 55% more likely.
People in the high genetic risk category who also reported poor sleep patterns were 122% more likely to be diagnosed with asthma than those with both a healthy sleep pattern and a low genetic risk.
Further analysis on a smaller group of people suggested that a healthy sleep pattern could reduce the risk of asthma in those at high genetic risk by 37.
They write: “The negative impact of sleep disorders on asthma, which is generally considered a chronic inflammatory disease, might be mediated by sleep-induced chronic inflammation. Previous studies have demonstrated that sleep disorders, such as unfavourable sleep duration and insomnia, are associated with chronic inflammation.
“In theory, the immune response to inflammation could generate pro-inflammatory cytokines that result in cellular infiltration and airway inflammation, further increasing the risk of asthma,” they write.
As this is an observational study, it cannot establish cause, and while the researchers acknowledge several limitations to their findings, they add: “Considering that poor sleep combined with high genetic susceptibility yielded a greater than twofold asthma risk, sleep patterns could be recommended as an effective lifestyle intervention to prevent future asthma, especially for individuals with high-risk genetics.”
Xiang B, Hu M, Yu H et al. Highlighting the importance of healthy sleep patterns in the risk of adult asthma under the combined effects of genetic susceptibility: a large-scale prospective cohort study of 455405 participants. BMJ Open Respiratory Research 4 April 2023; doi: 10.1136/bmjresp-2022-001535
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