Unless you have young children who act as your own personal alarm clocks (6am on the dot, every day without fail) many of us use weekends as a chance to indulge in a lie-in, hitting the snooze button and grabbing a few more hours sleep after a hectic working week. Except, this might actually be causing more harm than good.
Experts believe that ‘social jetlag’ - which sees our sleep habits change on a weekend compared to a weekday, can lead to unhealthy changes in our gut, resulting in a poorer diet and, in turn, increase the risk of illness.
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So, what can we do about it and is it really something to worry about? Here's everything you need to know about ‘social jet-lag’.
Going to sleep and waking up at very different times during the week, compared to the weekend, is known as having social jet-lag. In a new study conducted by Kings College London of 1,000 adults, scientists found that even a 90-minute difference in the midpoint of your night's sleep over the course of a normal week could influence the types of bacteria found in the human gut.
"Social jet-lag can encourage microbiota species which have unfavourable associations with your health," said Kate Bermingham, study author and senior nutrition scientist at health science company Zoe.
It is thought to affect more than 40% of the UK population, the study says, and is most common in teenagers and young adults, then tapers off as we age.
In the study, those who had social jetlag (16%) were more likely to eat a diet laden with potatoes, including crisps and chips, plus sugary drinks, and less fruit and nuts.
Previous research showed people with social jetlag ate less fibre than those with more consistent sleeping times. Other studies found social jetlag was linked to weight gain, illness and mental fatigue.
"Poor quality sleep impacts choices - and people crave higher carb or sugary foods," says Dr Bermingham.
Penny Weston, nutrition, wellness and fitness expert and the founder of MADE wellness centre says:
“Some gut bacteria are extremely important for our immune system, heart, weight and many other aspects of health. However, not all bacteria is good. For example, an unhealthy diet consisting of processed foods, alcohol and high amounts of sugar can link to poor gut health.”
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Weston added: "A consistent sleep pattern is not only important for health, but it can also affect our mood, memory, learning and creativity”.
How does sleep actually affect our diets? Weston says: "A lack of sleep can increase your appetite, and leave you craving carbohydrates and sugary foods. Not getting enough sleep can affect our hormones, by increasing ghrelin (known as ‘the hunger hormone’) levels but decreasing leptin levels, the hormone that helps us maintain a normal weight.
“If you have an imbalance of bacteria in your gut, it can lead to an inflammatory response. Therefore, eating a diet to encourage a healthy balance of bacteria will help ensure the bacteria in your gut are healthy and not having to fight off inflammation. I’m a firm believer in eating a healthy, balanced diet rich in all the essential nutrients that come from plant-based goodness, such as lots of fruit and vegetables. If you choose vegetables in a wide range of colours, then you will be stocking up on essential antioxidants to best help your body’s inflammatory response. They are also high in fibre, which is good for feeding gut bacteria and helping the process through the gut,” says Weston.
“Probiotics and fermented foods can also help promote healthy gut bacteria. Eating food such as yogurt, kefir, sauerkraut, kimchi and other fermented vegetables is really good for your gut health. Probiotic bacteria is sensitive to heat and moisture and products should ideally be refrigerated. Most labels will say whether a probiotic needs to be kept in the fridge or not,” Penny explains.
“Most adults should aim for at least seven hours of uninterrupted sleep per night, but the amount needed to allow you to wake up rested, refreshed and alert will vary from one person to another,” says Weston and she advises to try and keep this consistent.
"The blue light emitted by mobile phone screens and other tablets restrains the production of melatonin, the hormone that controls your sleep-wake cycle. This makes it hard to fall asleep and wake up the next day.
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“Creating a bedtime routine establishes habits that help our brains recognise when it’s time to sleep and it can help keep your mind focused on other tasks and encourage you to relax instead of worrying. Start with a warm bath and set the same time for bedtime so your body knows it’s time to get ready for sleep. You can also try some meditation,” suggests Weston.
