London – A new study shows shift workers, especially those working in night shifts, may be at a high risk of moderate to severe asthma. According to the study, published in the journal Thorax, around one in five employees in the developed world works permanent or rotating night shifts.
Shift work causes a person’s internal body clock (circadian rhythm) to be out of step with the external light and dark cycle. “This misalignment is associated with a heightened risk of various metabolic disorders, cardiovascular disease, and cancer,” said study authors from University of Manchester in the UK.
Symptoms of asthma, such as wheeze and airway whistling, vary considerably, according to the time of day or night, and the researchers wanted to find out if shift work might also be associated with an increased risk of asthma and/or its severity. They were also keen to explore how influential chronotype–individual body clock preference for morning or evening activity–and genetic predisposition to asthma might be.
All these participants were aged between 37 and 72, and either in paid employment or self-employed. Most (83 per cent) worked regular office hours, while 17 per cent worked shifts, around half of which (51 per cent) included night shifts. Shift patterns comprised: never or occasional night shifts; irregular or rotating night shifts; and permanent night shifts.
Compared with those working office hours, shift workers were more likely to be men, smokers, and living in urban areas and in more deprived neighbourhoods. They also drank less alcohol, slept fewer hours, and worked longer hours. Night shift workers are considered to be ‘owls’ and generally have poorer health.