Differences in sleep patterns between workdays and days off could affect the bacteria in your gut, which could impact your long-term health.

That is the finding of new research into the effect of ‘social jet lag’ – the changes to your body clock that are a result of irregular sleeping habits that occur when you wake up at different times on workdays compared to free days.

The study is the first to find links between these small changes and diet habits and diet quality, inflammation and gut microbiome composition.

Senior author Dr Wendy Hall, from King’s College London, said: “We know that major disruptions in sleep, such as shift work, can have a profound impact on your health.

“This is the first study to show that even small differences in sleep timings across the week seems to be linked to differences in gut bacterial species. Some of these associations were linked to dietary differences but our data also indicates that other, as yet unknown, factors may be involved.

“We need intervention trials to find out whether improving sleep time consistency can lead to beneficial changes in the gut microbiome and related health outcomes.”

Researchers looked at data from 934 people taking part in a nutritional study, comparing the gut microbiome of those with irregular and regular sleep patterns. What made this study different to previous research was that this group was made up mostly of healthy, lean participants who generally get more than seven hours of sleep each night.

One of the researchers’ key findings was around the midpoint of sleep, which is the halfway point between going to sleep and waking. They found that just a 90-minute difference in this midpoint was linked to differences in the composition of gut microbiome.

The make-up of the microbes in your gut can impact on your health, positively or negatively, and is affected by your diet. Certain types of microbes may be linked to a person’s risk of conditions including obesity, heart disease and diabetes.

‘Social jet lag’ is linked to poorer quality of diet, increased consumption of sugary drinks and eating less fruit and nuts – these factors could impact your gut microbiome.

First author and senior nutrition scientist Dr Kate Bermingham, said: “Sleep is a key pillar of health, and this research is particularly timely given the growing interest in circadian rhythms and the gut microbiome. Even a 90-minute difference in the mid-point of sleep can encourage microbiota species which have unfavourable associations with your health.”

Dr Sarah Berry, from King’s College London said: “Maintaining regular sleep patterns, so when we go to bed and when we wake each day, is an easily adjustable lifestyle behaviour we can all do, that may impact your health via your gut microbiome for the better.”

Read the study in European Journal of Nutrition.

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