The body clock and asthma

 Asthma.uk reports on some interesting research which might have wider application.

Dr Hannah Durrington is a consultant in respiratory medicine and a senior clinical lecturer at the University of Manchester. She has a particular interest in how our body clock (officially known as our circadian rhythm) can affect asthma symptoms.

We all have a body clock, which is influenced mainly by light and dark, and also by when we eat. Everyone’s body clocks ‘ticks’ slightly differently. For example, we all know if we’re more of a lark who’s happy to get up early and go to bed early, or an owl who enjoys sleeping in and staying up late. However, everyone’s body clock impacts on a number of biological processes and can influence how well we respond to medical treatments. For example, research has shown people can recover more quickly from surgery depending on what time of the day the operation is performed.

Hannah has carried out research that shows that asthma is certainly impacted by our body clock. She says asthma is “highly rhythmic” and if you have asthma you have probably already identified this for yourself. You might find your symptoms are worse at night and you wake up in the early hours with wheezing, breathlessness or chest tightness. Hannah’s research shows that this might be caused by changes in our bodies over the course of the day. Even in people without asthma, peak flow measurements (a quick test to measure air flow out of the lungs) will be lower at 4am than at midday. This is probably because everyone’s airways are tighter at night regardless of whether they have asthma, so in people with asthma whose airways are already tighter, further restriction can lead to more symptoms at night.

Research has also shown that our body clock could play an important role in monitoring the severity of asthma, particularly eosinophilic asthma which is a type of asthma associated with high levels of a white blood cell called eosinophils. To assess the severity of eosinophilic asthma, doctors measure the levels of eosinophils in blood or sputum. Hannah’s research has shown that these levels naturally vary over the course of the day. This means it could be helpful to time appointments around the variations in eosinophils to ensure doctors get the most accurate picture of a person’s asthma. Hannah has also looked into whether we are more likely to have a bad reaction to allergens – house dust mites, pollen etc – at different times of the day. A study in mice showed that they had a stronger allergic reaction to house dust mites if they were exposed to them shortly before their most active period of time (which for mice is at night). If the same thing was seen in humans, it could help people with asthma understand when they are more likely to be at risk of worsening symptoms caused by allergens and find ways to reduce their exposure or take preventative measures.

Ultimately, Hannah is keen to find out whether something called ‘chronotherapy’ could help people with asthma. Chronotherapy means timing when you take medication or other treatments according to when it’s likely to have the greatest benefit. Her research may help us to find out if there is an optimum time of day to use inhalers and take other asthma medication so it has the best chance of keeping asthma symptoms under control. “We don’t have all the answers yet, but it would be fantastic if, through research, we could find out what time of day asthma treatment is likely to give the greatest benefit to patients,” says Hannah.

.

Asthma research is severely underfunded

DID YOU KNOW: Research into respiratory diseases like asthma accounts for just 2% of all the medical research funding in the UK.

This underfunding is exactly why ashma.uk launched the 2021 Research Appeal...

Find out more